Last updated July 26, 2026
What does that abbreviation on the drawing actually mean? Below are 369 abbreviations and acronyms used on engineering and construction drawings, with the meaning, the discipline it belongs to, and a note on how it appears in practice. Use the filter box to jump straight to the one you are after.
The list leans Australian — it was compiled in an Australian drawing office — so where a US or UK drawing would use a different abbreviation for the same thing, the note says so. Always check the abbreviation legend in the front sheets of the drawing set you are reading: offices vary, and the set you have in front of you wins over any list.
The ones people ask about most
Some abbreviations need more than a line. These 16 have their own page — what the term means, how it is written on a sheet, what it gets confused with, and how the convention differs between Australian, UK and US drawings.
- What does AHD mean on a drawing?
- What does CLR mean on a drawing?
- What does CRS mean on a drawing?
- What does DIA mean on a drawing?
- What does FFL mean on a drawing?
- What does FGL mean on a drawing?
- What does NGL mean on a drawing?
- What does NTS mean on a drawing?
- What does O/A mean on a drawing?
- What does RL mean on a drawing?
- What does SHS mean on a drawing?
- What does SSL mean on a drawing?
- What does TOC mean on a drawing?
- What does TOS mean on a drawing?
- What does TYP mean on a drawing?
- What does UB mean on a drawing?
#
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| # | Number | General | On US drawings # can also mean pounds (weight), so AU practice prefers No. to keep it unambiguous. |
| /s | Snug fit or tightened (bolts) | Structural | Written 8.8/S – snug tight, the default for most AU connections; no tensioning or slip check needed. |
| /tb | Fully tensioned, bearing type (bolts) | Structural | Category suffix written with the grade first: 8.8/TB. AS 4100 Table 9.3.1 lists the categories. |
| /tf | Fully tensioned, friction type (bolts) | Structural | Written 8.8/TF – the only category where slip is not permitted, so surface treatment must be called up. |
| @ | At, used for spacing of repeated items | General | “N12 @ 200” means N12 bars at 200 mm centres. |
| °C | Degrees Celsius | Unit | AU/UK/ISO drawings use °C; US mechanical sheets and specs still give °F – check before reading setpoints. |
| Ø | Diameter | General | AS 1100 puts it before the size: Ø20 HOLE. Older AU drawings sometimes trail it, as in 20Ø. |
A
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| A | Ampere | Unit | Electrical ratings read 20 A or 20A. Beware: A also labels grid lines and detail keys on structural sheets. |
| A/C | Air Conditioning | Mechanical | Mechanical layouts tag it A/C or A/C UNIT; on electrical sheets AC is alternating current, so read the discipline. |
| A/H | After Hours | General | Site and title-block contact notes, e.g. A/H CONTACT 0400…; not a dimension or level abbreviation. |
| AB | As Built | General | Stamped on record sets or shown in the revision block. In US structural notes AB is Anchor Bolt – a real collision. |
| ABBR | Abbreviation | General | Heads the abbreviations table on the general notes sheet. |
| ABS | Absolute | General | Also the plastic ABS in pipe and fitting call-ups, common on drainage sheets – check the context. |
| ADD | Addendum | General | Tender or contract change document, listed in the revision block as ADD 1; not the same as ADD’L, additional. |
| AEC | Architecture, Engineering, and Construction | General | Industry grouping, not a drawing symbol; AECO adds Operations. Seen in BIM scopes and CAD standards documents. |
| AF | Across Flats | Mechanical | Nut and bolt-head size measured flat to flat, e.g. M12 NUT 19 A/F; across corners gives a larger figure. |
| AFFL | Above Finished Floor Level | Architectural | US drawings usually write AFF. |
| AFL | Above Floor Level | Architectural | Fixture and switch heights, e.g. GPO 300 AFL. US drawings write AFF, above finished floor. |
| AFL | Above Finished Level | Architectural | Same letters as Above Floor Level; some offices write AFFL to be explicit about the finished floor. |
| AG | Agricultural pipe drain | Civil | Slotted subsoil drain, called up as 100 AG IN FILTER SOCK. UK calls it a land drain, US a perforated underdrain. |
| AGL | Above Ground Level | Civil | Heights of poles, antennas and cranes. For site levels AU drawings use RL to AHD instead. |
| AHD | Australian Height Datum | Survey | Levels written RL 16.550 AHD; zero is about mean sea level. UK uses Ordnance Datum Newlyn, US NAVD88. |
| AHU | Air Handling Unit | Mechanical | Tagged AHU-01 on mechanical plans and equipment schedules; drives plant space and duct riser coordination. |
| AL | Aluminium | General | Also ALUM; US spelling aluminum. |
| APPROX | Approximately or Approximate | General | Flags a dimension not to be worked to; never scale or set out from an APPROX figure. |
| ARCH | Architect or Architectural | General | |
| ARRGT | Arrangement | General | Drawing title word – GENERAL ARRANGEMENT is usually shortened to GA; older sheets use ARRGT or ARRANGT. |
| AS | Australian Standard | General | Cited in notes as AS 3600; a joint Australian/NZ standard always carries the AS/NZS prefix, e.g. AS/NZS 1170. |
| ASCII | American Standard Code for Information Interchange | General | CAD context: an ASCII DXF or a comma-delimited survey point file, as opposed to a binary DWG. |
| ASSD | Assumed Datum | Survey | Levels not tied to AHD, e.g. ASSD DATUM RL 100.000. Never mix assumed and AHD levels on one sheet. |
| ASSY | Assembly | General | Shop-drawing titles, e.g. BEAM ASSY B12; a nested one is a SUB-ASSY, and it pairs with a parts or mark list. |
| ATF | Along Top Flange | Structural | Steel detailing direction: holes or cleats measured along the beam top flange, e.g. HOLES @ 300 ATF. |
| AUTO | Automatic | General | Mostly equipment call-ups: AUTO AIR VENT, AUTO SLIDING DOOR. |
| AUX | Auxiliary | General | Switchboard and equipment schedules, e.g. AUX CONTACT, AUX SUPPLY. |
| AVG | Average | General |
B
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| B | Basin or Bottom | General | Reinforcement notation: N12-200 B is the bottom layer, T the top. On plumbing plans B tags a basin. |
| BCA | Building Code of Australia | General | Now published as Volumes 1 and 2 of the NCC. |
| BDY | Boundary | Survey | |
| BIM | Building Information Modelling | General | |
| BLDG | Building | Architectural | |
| BM | Bench Mark | Survey | A fixed point of known reduced level. |
| BNS | Business Network Services | General | |
| BOT | Bottom | General | Level and face call-ups, e.g. BOT OF BEAM RL 12.400; BTM means the same. US steel drawings write BOS. |
| BQ | Bendable Quality | Structural | Plate and bar quality note. In AU/UK contract documents BQ far more often means Bill of Quantities – read the context. |
| BRG | Bearing | General | Survey setout gives it in degrees, minutes, seconds; mechanical and bridge sheets use BRG for the bearing component. |
| BRS | Brass | Mechanical | |
| BSP | British Standard Pipe | Mechanical | Threads: BSPT tapered and BSPP parallel are the AU/NZ/UK series; US pipework uses NPT and the two do not mate. |
| BT | Boundary Trap | Civil | Sanitary drainage trap at the property boundary, drawn with an inspection opening and vent; an AU water-authority item. |
| BT | Bath Tub | Architectural | Fixture tag on wet-area plans; the same letters mean Boundary Trap on a drainage plan. |
| BTM | Bottom | General | Interchangeable with BOT; steel detailers write BTM FLG for the bottom flange. |
| BW | Both Ways | Structural | Reinforcement: N12-200 BW means 12 mm bars at 200 crs each way. On steel details BW can instead mean Butt Weld. |
C
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| C | C shaped steel purlin | Structural | Cold-formed purlin to AS/NZS 4600, sized like C20019 – 200 mm deep, 1.9 mm thick; Z sections are the lapping alternative. |
| C/C | Cross Centres | General | Spacing between centres; AU sheets more often write CRS or CTS, US and UK write O.C. Bolt gauges are given as cross centres. |
| CAD | Computer Aided Design | General | Also Computer Aided Drafting/Draughting. |
| CAM | Computer Aided Manufacture | General | Fabrication context – CAM output such as DSTV/NC1 files drives the drill line, so drawing and model must agree. |
| CAP | Capacity | General | Collides with the pipe end CAP and a cap plate (CAP PL 10 THK); capacity is normally followed by units. |
| CBORE | Counterbore | Mechanical | Hole note, e.g. 10 DIA THRU, 16 CBORE 8 DEEP; also shown by the ISO/ASME counterbore symbol. Compare CSK, countersink. |
| CCTV | Closed Circuit TeleVision | Electrical | Security layouts tag cameras CCTV-01. On drainage drawings CCTV means a pipe camera survey, not a camera install. |
| CFW | Continuous Fillet Weld | Structural | Steel detailing: 6 CFW is a 6 mm continuous fillet weld, welding to AS/NZS 1554. Intermittent welds show a pitch instead. |
| CH HD | Cheese Head | Mechanical | Screw head call-up, e.g. M6 x 20 CH HD; slotted cheese head is ISO 1207. US drawings favour pan or fillister heads. |
| CHAM | Chamfer | General | Written 20 x 20 CHAM on concrete edges and 2 x 45 deg CHAM on machined parts; in formwork it is a splayed fillet. |
| CHCL | Channel | Structural | AU channels are PFC, parallel flange channel, to AS/NZS 3679.1; older sheets show TFC taper flange. CH or CHAN also seen. |
| CHS | Circular Hollow Section | Structural | Sized OD x wall, e.g. 168.3 x 4.8 CHS, to AS/NZS 1163. US drawings call the same member round HSS or pipe. |
| CI | Cast Iron | Civil | Legacy pipe and cover material; AU water mains now specify DICL, ductile iron cement lined. Do not read CI as cast in. |
| CIRC | Circumference or Circle | General | Also short for circulating on hydraulic and mechanical sheets, e.g. CIRC PUMP – context separates the two. |
| CJ | Construction Joint, or Control Joint depending on context | Structural | |
| CKS | Countersink | Mechanical | Usually written CSK: ‘Ø6.5 THRU, CSK Ø12 x 90°’ – hole size first, then cone diameter and included angle. |
| CL | Center Line | General | Drawn as a long-short chain line per AS 1100 and ISO 128, with the CL symbol at the dimension. AU/UK spell it centre line. |
| CLG | Ceiling | Architectural | Reads CLG HT 2700 or SUSP CLG on architectural sheets. Control joint is CJ; construction joint is CNJ or CJ. |
| CLR | Clearance | General | A physical gap, 50 CLR; on reinforcement notes it means clear cover, 40 CLR TO TIES. Treat MIN CLR as a limit. |
| CMU | Concrete Masonry Unit | Architectural | US term for a concrete block; AU/UK drawings say blockwork or CONC BLK, usually the 190 series. |
| CNC | Computer Numerical Control | Mechanical | Seen as CNC PROFILE CUT on plate details; the cut file comes off the model, so avoid approximate or stacked dims. |
| CNJ | Construction Joint | Structural | Concrete pour break, shown as a heavy line marked CNJ. Distinguish from CJ control joint and expansion/isolation joints. |
| CNR | Corner | General | Setout notes, e.g. SE CNR OF BLDG, usually paired with a coordinate or grid reference. |
| COEF | Coefficient | General | |
| COL | Column | Structural | Keyed to a column schedule, e.g. COL C1; on plan the grid intersection is normally the column centreline. |
| COMMS | Communications | Electrical | AU usage: COMMS ROOM, COMMS CUPBOARD. US drawings label the same space TEL/TELE or IT, UK often data. |
| CONC | Concrete (also Concentric in mechanical/piping work) | Structural | On structural and architectural sheets CONC reads Concrete; a piping ‘CONC RED’ is a concentric reducer. |
| CONN | Connection | Structural | Steel detailing: ‘CONN TYPE B – SEE DET 4/S501’ keys a joint to a standard connection detail. |
| CONT | Continuous | General | ‘N16 CONT’ = bar runs through unbroken. In note blocks CONT can instead mean ‘continued’ – read context. |
| CP | Chrome Plated | Mechanical | Chrome Plated is the tapware/fixture sense; on civil and survey sheets CP is usually Control Point or Concrete Pipe. |
| CRS | Cold Rolled Steel | Structural | On AU structural drawings CRS far more often means centres: ‘N12 @ 200 CRS’ = bars at 200 mm spacing. |
| CS | Cleaners Sink | Mechanical | Hydraulic fixture tag, sits alongside KS (kitchen sink) and LT (laundry trough) on fixture layouts. |
| CS | Cast Steel | Mechanical | In piping and pipe-spec notes CS almost always reads Carbon Steel, not Cast Steel. |
| CSK HD | Countersunk Head | Mechanical | ‘M10 x 30 CSK HD’ – head finishes flush with the surface, unlike CH HD or HEX HD which stand proud. |
| CT | Controller | Electrical | On electrical drawings CT is far more often Current Transformer; cable-tray runs are also tagged CT. |
| CTR | Contour | Survey | Collides with CTR = centre. Survey and civil plans more often label a contour by its RL, e.g. ‘42.5’. |
| CTR(S) | Centre/S | General | AU/UK spell ‘centre’, US ‘center’ – same tag either way; US spacing notes use O.C. instead. |
| CTRL | Control | General | Seen as CTRL JT (control joint) on slabs and paving, and CTRL PANEL on mechanical and electrical sheets. |
| CTRS | Centers | General | US spelling of the same tag; US drawings usually write spacing as O.C. rather than CTRS. |
| CTRS | Centres | General | ‘N12-200 CTRS’ = bars at 200 mm spacing; a US drawing writes the same thing as ‘#4 @ 8″ O.C.’ |
| CU | Dental Cuspidor | Mechanical | Dental spittoon on health-fitout hydraulic plans. Not Cu (copper) – the chemical symbol has a lower-case u. |
| CUP HD | Cup Head | Mechanical | ‘M12 CUP HD BOLT’ – domed head with square neck that bites timber; UK/US call it a coach or carriage bolt. |
| CVR | Cover | Structural | In RC work this is concrete cover to reinforcement: ’40 CVR TO EARTH FACE’. On civil plans it can be a pit lid. |
| CYL | Cylinder | Mechanical | In hydraulic services CYL is usually the hot-water cylinder; in mechanical part lists it is the cylinder itself. |
D
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| DAR | Dressed All Round | Architectural | AU/NZ timber: planed on all four faces, so ’90 x 45 DAR’ is the finished size. US equivalent is S4S. |
| DB | Distribution Board | Electrical | MSB = Main Switchboard. |
| DD | Design Drawing | General | Carries the engineer’s design intent; contrast WD (working drawing) and the fabricator’s shop drawings. |
| DED | Dedendum | Mechanical | Gear tooth depth below the pitch circle; pairs with addendum (ADD) in a gear data table with PCD, PA and DP. |
| DET | Detail | General | Reads ‘DET 3 / S204’ – detail 3 on sheet S204; the bubble on the parent view carries the same number. |
| DIA | Diameter | General | AU/ISO practice puts the Ø symbol before the value (Ø20); ’20 DIA’ written after the value is the older habit. |
| DIAG | Diagonal | Structural | Steel bracing note: ‘DIAG BRACE TO EVERY 4TH BAY’. Collides with DIAG = diagram. |
| DIAG | Diagram | General | Same tag as diagonal – ‘WIRING DIAG’ vs ‘DIAG BRACE’. Spell it out if both appear in one set. |
| DICL | Ductile Iron Cement Lined (pipe) | Civil | AU water-main callout: ‘DN300 DICL’. US drawings say DIP (ductile iron pipe); UK usually just DI. |
| DIM | Dimension | General | AU drawings give dimensions in mm with no unit on each number – the title block states ‘ALL DIM IN MM UNO’ (AS 1100). |
| DIST | Distance | General | On electrical sheets DIST is distribution (DIST BOARD), not distance. |
| DL | Dead Load | Structural | Permanent action. |
| DN | Diameter Nominal | Mechanical | DN100 is a nominal designator, not true ID or OD; US equivalent is NPS 4. On stair and ramp plans DN means ‘down’. |
| DP | Diametral Pitch | Mechanical | Imperial gear term – teeth per inch of pitch diameter; metric gear drawings use module (m) instead. |
| DP | Down Pipe | Mechanical | ‘100 Ø DP’ on roof plans. US calls it a downspout (DS), UK a rainwater pipe (RWP). Also collides with diametral pitch. |
| DPC | Damp Proof Course | Architectural | |
| DR | Dryer | Architectural | Laundry layouts pair DR with WM and LT. Some architectural sets use DR for ‘door’ – check the legend. |
| DRG | Drawing | General | UK and older AU form; DWG is now the common AU abbreviation and is also the AutoCAD file extension. |
| DW | Dishwasher | Mechanical | Kitchen appliance needing a water point and a waste. On some hydraulic sheets DW instead means domestic water. |
| DWG | Drawing | General | Both a title-block field (‘DWG No.’) and the AutoCAD file format – same three letters, two meanings. |
| DWG(S) | Drawing/S | General | |
| DWL | Dowel | Structural | Also DWLS for dowels. |
E
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| E | Modulus of Elasticity | Structural | Young’s modulus. AU notes give E in MPa – 200,000 for steel, roughly 30,000 for normal concrete; US uses ksi/psi. |
| EA | Equal Angle (steel) | Structural | ’90 x 90 x 8 EA’ per AS/NZS 3679.1; US writes L3x3x3/8. In quantity columns EA means ‘each’ instead. |
| EF | Each Face | Structural | ‘N12-200 EF’ = N12 at 200 crs in each face of a wall or slab; compare EW (each way) and NF/FF. |
| EGL | Existing Ground Level | Civil | |
| EJ | Expansion Joint | Structural | |
| EL | Elevated Level | General | AU/NZ use RL for a level to AHD; EL written as ‘EL 16.550’ is the US and civil habit. |
| EL | Elevation | General | Two senses: a level to datum (‘EL 16.550’, US/civil) and a vertical view. AU sets use RL for the level. |
| ELEC | Electrical | Electrical | Service tag on coordination plans (ELEC, MECH, HYD, FIRE) and in scope notes like ‘ELEC BY OTHERS’. |
| ELEV | Elevation | Architectural | On AU sets ELEV is the vertical view (‘NORTH ELEV’); a height above datum is RL, not ELEV. |
| EQ | Equal | General | ‘EQ | EQ | EQ’ between grids means space evenly – the overall dimension must still be shown. |
| EQUIP | Equipment | General | |
| EQUIV | Equivalent | General | Substitution note: ‘GALV BOLTS OR APPROVED EQUIV’ signals an alternative product may be submitted. |
| EW | Each Way | Structural | ‘N12-200 EW’ = N12 bars at 200 crs in both directions. Mesh is already two-way, so EW is not added to it. |
| EWB | Electric Water Boiler | Mechanical | Tearoom fixture needing both a GPO and a water point, so it turns up on the ELEC and HYD plans. |
| EWC | Electric Water Cooler | Mechanical | Standard US plumbing tag for a drinking fountain or water cooler; AU sets more often write DF or chilled water unit. |
| EXIST | Existing | General | Also seen as EXG, EXTG or EX. |
| EXT | External | General | Pairs with INT. US drawings prefer EXTR for exterior; in note blocks EXT can also mean ‘extension’. |
F
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| FB | Footing Beam | Structural | On AU steelwork FB is Flat Bar (’50 x 10 FB’); as a footing mark it reads FB1, FB2 on the footing plan. |
| F’c | Characteristic Concrete Strength | Structural | AS 3600 notation, MPa at 28 days: ‘N32’ concrete is f’c = 32 MPa. US drawings give f’c in psi, e.g. 4000 psi. |
| FCL | Finished Ceiling Level | Architectural | |
| FCU | Fan Coil Unit | Mechanical | Tagged FCU-01, FCU-02 on mechanical plans and keyed to the equipment schedule for duty and size. |
| FFL | Finished Floor Level | Architectural | Written ‘FFL 16,550’ to AHD – top of finishes, so it sits above SSL by the floor build-up. US writes FIN FL EL or AFF. |
| FGL | Finished Ground Level | Civil | |
| FHR | Fire Hose Reel | Mechanical | Fire services tag, usually cabinet-mounted near an exit; AS 2441 covers installation. Not the same as FH (hydrant). |
| FIG | Figure | General | The list currently has FIQ, which appears to be a typo. |
| FILL HD | Fillister Head | Mechanical | Slotted head with a domed top and deeper slot than a cheese head; imperial-era term, rare on modern AU drawings. |
| FIN | Finish or Finished | Architectural | |
| FIQ | Figure | General | |
| FL | Flat or Flat Plate | Structural | 100 x 10 FL = 100 mm wide x 10 mm thick flat bar. Don’t read it as Floor Level – same letters, different drawing. |
| FL | Floor Level | Architectural | Generic – AU sets qualify it as FFL (finished) or SSL (structural slab). FL alone on a section is ambiguous. |
| FLG | Flange | Structural | Steel: the top or bottom flange of a UB/UC. Piping: a flanged joint, e.g. DN150 FLG. |
| FOC | Fibre Optic Cable | Electrical | Collision: also read as Face of Concrete, or Face of Curb on US civil plans. Check the drawing legend. |
| FRL | Fire Resistance Level | Architectural | The Australian/NZ fire rating notation, given as three numbers for structural adequacy / integrity / insulation, e.g. -/60/60. |
| FS | Far Side | Structural | Reinforcement: N12-200 FS puts bars on the face away from the viewer; NS is the near side. |
| FSBL | Full Strength Butt Weld | Structural | AS/NZS 1554.1 weld; shown against the weld symbol with the SP or GP category noted. |
| FSL | Finished Surface Level | Civil | Also read as Finished Slab Level. |
| FTG | Footing | Structural | AU/UK footing covers pads, strips and pile caps; US drawings label the same work FND/foundation. |
| FTP | Fibre Termination Panel (fibre optical cable) | Electrical | Comms risers: where incoming fibre terminates before patch leads. Not File Transfer Protocol. |
| FW | Fillet Weld | Structural | Sized by leg length on the weld symbol – ‘6 FW’. CFW means the fillet runs continuous. AS 1101.3. |
| FWF | From Web Face (steel) | Structural | Hole and cleat dimensions taken from the face of the beam web, not from its centreline. |
G
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| GA | General Arrangement | General | The overall assembly and grid sheet that details are cross-referenced from; more an AU/UK term than US. |
| GALV | Galvanized | General | Usually qualified HDG – hot dip galvanized to AS/NZS 4680, coating class quoted as 600 g/m2. |
| GCI | Galvanized corrugated iron. | Architectural | Older AU term for corrugated roof and wall sheeting; now specified as profiled steel sheet. |
| GD | Grid | General | Grid lines run letters one way and numbers the other, so GD B/4 pins one intersection. |
| GDA | Geocentric Datum of Australia (GDA94, GDA2020) | Survey | The horizontal datum, the companion to AHD for levels. |
| GF | Ground Floor | Architectural | FF = First Floor, GFL = Ground Floor Level. |
| GI | Galvanized Iron | General | Legacy label – the material is really galvanized steel. Still common on older AU and imported drawings. |
| GIP | Galvanized Iron Pipe | Mechanical | Sized by DN with BSP threads, e.g. DN50 GIP; modern AU specs say galvanized steel pipe. |
| GIS | Geographic Information System | Survey | Survey exports carry GDA2020/MGA coordinates. Beware: GIS also = Gas Insulated Switchgear on HV drawings. |
| GL | Ground Level (also used for Grid Line | Civil | Read from context). |
| GPO | General Purpose Outlet | Electrical | AU word for a power point. US drawings say receptacle or outlet; UK says 13 A socket outlet. |
| GR | Grade | General | Two senses – material grade (GR300 steel, 8.8 bolts) and ground grade/level in civil work. |
| GRF | Geometric Reference Frame | Mechanical | GD&T framework a geometric tolerance is measured from; most drawings label it DRF, Datum Reference Frame. |
| GSM | Global System for Mobile Communications (originally “Groupe Special Mobile” in French) | Electrical | Careful: lower-case gsm on a spec is grams per square metre – membrane and coating mass, not mobile. |
H
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| H | Prewash Hose Reel | Mechanical | Fixture tag on hydraulic layouts, defined in the fixture schedule; H elsewhere reads as Height. |
| HD | Head | Mechanical | As in M12 HEX HD BOLT. In AU structural work an HD bolt is instead a holding-down bolt cast into concrete. |
| HDG | Hot Dip Galvanised | Structural | |
| HEX HD | Hexagon Head | Mechanical | Written M20 x 60 HEX HD BOLT; AF gives the spanner size across flats. AS 1111 commercial bolt series. |
| HOR | Horizontal | General | Paired with VER/VERT; HORIZ is the commoner form on AU drawings. |
| HORIZ | Horizontal | General | Used for bar direction in walls – ‘N12-200 HORIZ EF’, with VERT bars running the other way. |
| HP | High Pressure | Mechanical | Also High Point on drainage and road plans (LP marks the sag) and Horsepower on older plant sheets. |
| HRA | Rockwell Hardness A | Mechanical | Quoted as ’60 HRA’; the A scale is rare on construction details – HRC is the usual one. |
| HRB | Rockwell Hardness B | Mechanical | B scale, 1.6 mm ball at 100 kgf, for softer steel, brass and aluminium; written ’85 HRB’. |
| HRC | Rockwell Hardness C | Mechanical | C scale, diamond cone at 150 kgf, for hardened steel. On electrical drawings HRC = High Rupturing Capacity. |
| HS | High Strength | Structural | Modern callout is ‘M20 8.8/TF’ – high strength structural bolt to AS/NZS 1252, fully tensioned. |
| HT | Height | General | Context matters: HT also reads as Heat Treatment on machining details and High Tension on electrical plans. |
| HTS | High-Tensile Steel | Structural | Superseded for reinforcement – current AU bar is grade 500N to AS/NZS 4671, tagged N12, N16. |
| HV | Diamond Pyramid Hardness Number (Vickers) | Mechanical | Written ‘250 HV30’ – hardness then test load in kgf. On electrical drawings HV means High Voltage. |
| HVAC | Heating, Ventilation and Air Conditioning | Mechanical | |
| HWB | Hair Wash Basin | Mechanical | Fixture tag on salon and medical hydraulic layouts; not HWU, which is a hot water unit. |
I
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| I | Moment of Inertia | Structural | Properly the second moment of area, in mm^4; tabulated as Ix and Iy in the steel section tables. |
| ID | Inside Diameter | Mechanical | Pipe bore – ‘ID 150’; paired with OD. On equipment schedules ID can instead mean Identification. |
| IE | Invert Elevation | Civil | US drainage term; AU/NZ drawings write IL. The invert is the inside bottom of the pipe, not its centreline. |
| IFC | Issued For Construction | General | In a BIM context, Industry Foundation Classes. |
| IL | Invert Level | Civil | Written ‘IL 12.350’ at a pit, to AHD; pipe runs are set out invert to invert with a stated grade. |
| INSUL | Insulation | Architectural | |
| INT | Internal | General | Also read as Intermediate on framing plans and Interior on US architectural sheets. |
| IO | Inspection Opening | Mechanical | Capped access on a sanitary drain, AS/NZS 3500.2; sits alongside IP and ORG on the same plan. |
| IP | Intersection Point | Civil | Road and pipe setout: where two straights meet; TP marks where the curve leaves the tangent. Also IP66 ratings. |
| ISO | International Organization for Standardization | General | On drawings ISO often just labels an isometric view. Sheet sizes A0-A4 come from ISO 216. |
J
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| JIS | Japanese Industrial Standards | General | Shows up on imported plant; JIS flange bolt patterns do not match AS or ANSI drilling. |
| JT | Joint | General | Nearly always qualified – CJ/CNJ construction, EJ expansion, ISJ isolation – and the type sets bar continuity. |
| JUNC | Junction | Civil | Drainage and road plans, often with the angle: ‘DN150 JUNC 45 deg’. |
K
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| kHz | Kilohertz | Unit | 1 kHz = 1000 Hz. Lower-case k for kilo, capital H because hertz is a person’s name. |
| kN | Kilonewton | Structural | The standard unit of load on structural drawings. |
| kPa | Kilopascal | Structural | Used for distributed loads and pressures. |
| KS | Kitchen Sink | Mechanical | Hydraulic fixture tag, alongside CS cleaners sink and LT/TR laundry trough. |
| kW | Kilowatt | Electrical | |
| KWh | Kilowatt hour – unit of electrical energy (as measured by a meter) | Unit | Energy, not power: 1 kWh is 1 kW drawn for an hour. Labels the energy/revenue meter on switchboard drawings. |
L
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| L | Steel Angle | Structural | AU drawings write angles as EA/UA – ‘100x100x10 EA’ – where US and European practice writes L100x100x10. |
| LAN | Local Area Network | Electrical | Data outlets tag back to a patch panel at the MDF or comms rack; cabling to AS/NZS 3080. |
| LG | Length | General | Bar and member lists: ‘N16 x 6000 LG’. On architectural plans LG can instead mean Lower Ground. |
| LGX | Line Group Cross (Connector, fibre optical cable) | Electrical | On comms drawings LGX names a fibre patch-panel housing/cassette format rather than a connector type. |
| LH | Left Hand | General | Handing is stated from a nominated viewing side; mirrored parts are marked LH/RH off one detail. |
| LL | Live Load | Structural | Imposed action. |
| LMC | Least Material Condition | Mechanical | GD&T: circled L after the tolerance – hole at its largest, pin at its smallest. MMC is the opposite case. |
| LONG | Longitudinal | Structural | LONG bars run along the member, TRANS across: ‘LONG N16-200, TRANS N12-300’. |
| LPG | Liquefied Petroleum Gas | Mechanical | Heavier than air, so tank, pit and drain clearances govern; storage and handling to AS/NZS 1596. |
| LT | Laundry Trough | Mechanical | Fixture tag (TR on some drawings). On electrical plans LT reads as Light or Low Tension instead. |
| LVL | Laminated Veneer Lumber | Structural | Engineered structural timber. |
M
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| m | Metres (AU/UK spelling) or Meters (US spelling) | Unit | AU/UK plans dimension in mm with no unit shown; metres appear only for levels, chainages and areas. |
| M/C | Machine | Mechanical | Shop-note shorthand, as in ‘M/C ALL OVER’. US drawings usually write MACH. |
| MATL | Material | General | Part list and schedule column: ‘MATL: GRADE 350 PLATE to AS/NZS 3678’. |
| MAX | Maximum | General | Written after the value – ‘2400 MAX’; with MIN it forms a one-sided limit instead of a plus/minus tolerance. |
| MDF | Main Distribution Frame (Telecommunications) | Electrical | Comms rooms. On architectural or joinery drawings MDF is Medium Density Fibreboard – check the discipline. |
| MECH | Mechanical | General | Mechanical services or the mechanical discipline. |
| MFR | Manufacturer | General | Often ‘TO MFR’S DETAILS’, shifting the detail to the supplier. MFG is manufacturing, not the manufacturer. |
| MGA | Map Grid of Australia (MGA94, MGA2020) | Survey | The national projected coordinate grid. |
| MH | Manhole | Civil | Access chamber on a sewer or drain. |
| MHz | Megahertz | Unit | 1 MHz = 10^6 Hz. Case matters: mHz would be millihertz. |
| MI | Malleable Iron | Mechanical | Pipe fittings and brackets. Not CI (cast iron) or ductile iron – different strength and weldability. |
| Micky Mouse | A toy project, of very low quality. | General | Drafting-room slang, never lettered on a drawing; usually spelled Mickey Mouse. |
| MIN | Minimum | General | Follows the value: ’40 MIN cover’. A MIN/MAX pair states limits with no nominal size. |
| MISC | Miscellaneous | General | MISC STEEL or MISC METALS is the package of handrails, ladders and lintels outside the main frame. |
| mm | Millimetres | Unit | AU/UK drawings are in mm with the unit omitted, so a bare 2400 is 2400 mm; levels are given in metres. |
| MMC | Maximum Material Condition | Mechanical | GD&T: the circled M after a tolerance. Most material = smallest hole, largest shaft. Opposite of LMC. |
| MOD | Modification | General | On gear drawings MOD is the module (MOD 2 = 2 mm tooth module), not a modification – read the gear data table. |
| MPa | Megapascal | Structural | Used for concrete strength (e.g. 32 MPa) and steel grades. |
| MS | Mild Steel | Structural | Legacy term. AU drawings now call up a grade: Gr300 to AS/NZS 3679.1 for sections, AS/NZS 3678 for plate. |
| MTG | Mounting | Mechanical | Appears as MTG HOLES or MTG PLT on equipment and bracket details. |
| MUSH HD | Mushroom Head | Mechanical | Domed head over a square neck – the coach/carriage bolt family. AU drawings more often say CUP HD. |
N
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| N | Normal-ductility deformed reinforcing bar to AS/NZS 4671, grade 500N – N12 is a 12 mm deformed bar | Structural | |
| N.S.O.P. | Not Shown On Plan | General | Put against an item drawn only in section or elevation, so the reader does not hunt for it on the plan. |
| N/A | Not Applicable | General | |
| NB | Nominal Bore | Civil | Nominal internal pipe size, used interchangeably with DN in Australia. |
| NC | Normally Closed | Electrical | De-energised state, paired with NO. Beware NC also = Numerical Control, or US Unified Coarse thread. |
| NCC | National Construction Code | General | The current Australian building code, incorporating the Building Code of Australia. |
| NEG | Negative | General | |
| NET | Network | General | On schedules NET means net rather than gross quantity or weight – read the column heading, not the abbreviation. |
| NGL | Natural Ground Level | Civil | |
| NO | Normally Open | Electrical | The counterpart to the listed NC, Normally Closed. |
| No. | Number | General | AU/UK quantity prefix: ‘4 No. M20 bolts’ means four bolts. US drawings use # or QTY. |
| NOM | Nominal | General | A label, not a measured size – DN100 pipe has no 100 mm dimension, and nominal timber exceeds the dressed size. |
| NS | Near Side | Structural | Reo and plate faces: ‘N12-200 EW NS’, with FS the opposite face of the wall or member. |
| NS | Nominal Size | Mechanical | Older pipe usage. AU/NZ now size pipe as DN (DN100); the US equivalent is NPS. |
| NTS | Not To Scale | General | Under a detail, or ‘SCALE: NTS’ in the title block. A single out-of-scale dimension is underlined instead. |
| NZS | New Zealand Standard | General | Joint standards are AS/NZS (e.g. AS/NZS 3679.1). NZS alone is NZ-only, like NZS 3101 for concrete. |
O
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| O/A | Overall | General | |
| OCT | Octagon | Mechanical | Like hex, octagonal bar is sized across the flats (A/F), not across the corners. |
| OD | Outside Diameter | Mechanical | Pairs with ID; for a given DN the OD is fixed and wall thickness varies. In UK survey work OD is Ordnance Datum. |
| OPP | Opposite | General | Opposite hand, mirrored. |
| OPT | Optional | General | |
| OSD | On-Site Detention | Civil | Stormwater detention required by many Australian councils. |
P
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| P | Pipe | Mechanical | Rarely alone – usually a tag read off the pipe schedule. In sanitary work P also means a P-trap, as in WC(P). |
| PA | Pressure Angle | Mechanical | Gear tooth geometry, normally 20 deg (14.5 deg on old work). Listed in the gear data table, not on the view. |
| PAR | Parallel | General | UK joinery uses PAR for Planed All Round – the equivalent of the AU DAR. Check the discipline first. |
| PATT | Pattern | Mechanical | Foundry work: the pattern number carried in the parts list, e.g. PATT No. 1234. |
| PC | Precast | Structural | Precast concrete. |
| PCD | Pitch Circle Diameter | Mechanical | Bolt circles: ‘8 HOLES Ø22 EQ SP ON 400 PCD’. US drawings say bolt circle or BC. |
| PFC | Parallel Flange Channel | Structural | Written 250 PFC, to AS/NZS 3679.1. Superseded taper-flange TFC/RSC; US equivalent is a C or MC channel. |
| PL | Plate | Structural | Steel detailing puts thickness first: PL 10 x 150 x 300. Plate grades are to AS/NZS 3678. |
| PL | Pipeline | Civil | Context decides: the same PL is Plate in steel detailing and Property Line on US site plans. |
| POS | Positive | Electrical | With NEG, labels DC polarity; schematics prefer the + and – symbols. |
| POSN | Position | General | AU/UK contraction. US lists abbreviate position as POS, which then collides with positive. |
| PREFAB | Prefabricated | General | |
| PT | Part | General | PT No. keys the balloons to the parts list. On concrete drawings PT usually means post-tensioned. |
| PT | Pressure Tapping | Mechanical | A small threaded port for a gauge, tagged with size and thread: PT 1/2 BSP. |
| PVC | Poly Vinyl Chloride | Mechanical | AU pipework is really PVC-U: AS/NZS 1260 for DWV, AS/NZS 1477 for pressure. Sized as DN, not OD. |
Q
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| QTY | Quantity | General | Parts-list column heading. AU/UK notes say the same thing as ‘4 No.’ |
R
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| R | Radius | General | Prefix the value: R25, never 25R. A full circle is dimensioned as a diameter (Ø) instead. |
| Ra | Roughness Value | Mechanical | Arithmetic mean roughness in µm, written in the surface-finish symbol as Ra 3.2. Lower is smoother. |
| RAD | Radius or radial | General | Used in notes – ‘RAD ALL CORNERS’ – while the dimension itself is written R25. |
| RC | Reinforced Concrete | Structural | |
| RD | Round | Mechanical | Round bar is normally just Ø25. Watch context: RD is Road on site plans and Roof Drain in US plumbing. |
| RECT | Rectangular | General | |
| REF | Reference | General | A REF dimension is information only and is not inspected; usually bracketed, e.g. (450) or 450 REF. |
| REINF | Reinforcement | Structural | AU bars are N12/N16 to AS/NZS 4671, spaced ‘N12-200’ or ‘@ 200 crs’; mesh is SL82. US uses #4 = 4/8 in. |
| REQD | Required | General | |
| REV | Revision | General | Cloud and revision triangle mark the change; many AU offices letter preliminary issues and number construction issues. |
| RFI | Request For Information | General | |
| RH | Right Hand | General | RH threads are the default – only LH gets called up. Door handing must state the side you view from. |
| RHS | Rectangular Hollow Section (rarely Rolled Hollow Section) | Structural | Written 100x50x4.0 RHS to AS/NZS 1163. Square is SHS, round CHS; the US calls all three HSS. |
| RL | Reduced Level or Relative Level | Survey | Written RL 24.350 – metres to 3 places, to AHD in AU – while plan dimensions are mm. US drawings use EL. |
| RO | Reverse Osmosis (water treatment) | Mechanical | Watch out: on US architectural drawings RO is Rough Opening. |
| RSA | Rolled Steel Angle | Structural | Older UK term. AU drawings use EA or UA – 100x100x10 EA – to AS/NZS 3679.1. |
| RSC | Rolled Steel Channel | Structural | Legacy taper-flange channel. AU and UK now use PFC, so old RSC sizes won’t match current section tables. |
| RSJ | Rolled Steel Joist | Structural | Legacy taper-flange I-section; AU equivalents are UB and UC. Still UK trade slang for any steel beam. |
S
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| S | Sink | Mechanical | Fixture tag on hydraulic plans, usually qualified – KS kitchen sink, CS cleaners sink. |
| S | Snug fit or tightened (bolts) | Structural | Part of the AS 4100 bolt category: 8.8/S is snug-tight, against 8.8/TB or 8.8/TF fully tensioned. |
| SAN | Sanitary | Mechanical | Hydraulic drawings pair SAN (sanitary/sewer drainage) with SW (stormwater); design to AS/NZS 3500.2. |
| SDU | Sanitary Disposal Unit | Architectural | Fixture-schedule tag for the sanitary bin in female and accessible WCs – a fitting, not a plumbed fixture. |
| SECT | Section | General | View title reads SECT A-A, keyed to the cutting-plane arrows on the plan; AS 1100.101 sets the convention. |
| SF | Strip Footing | Structural | Tagged SF1, SF2 keying to a footing schedule; watch the clash with SF = Spot Face on machining drawings. |
| SF | Spot Face | Mechanical | Machining callout like SF 25 DIA – a shallow flat face around a hole so a nut or washer seats square. |
| SFL | Structural Finished Level | Structural | Also read as Structural Floor Level. Top of slab before toppings: FFL = SFL + screed + floor covering. |
| SH | Sheet | General | Title-block form is SH 3 OF 8; SHT is the other common spelling. |
| SHR | Shower | Mechanical | Fixture tag on wet-area plans with WC and WB; the wet-area waterproofing itself is to AS 3740. |
| SHS | Square Hollow Section | Structural | Written 100x100x6.0 SHS, to AS/NZS 1163. US drawings call the same member HSS. |
| SIM | Similar | General | Reads “3/S12 SIM” – same detail with minor variation. Often means handed; confirm the hand before fabricating. |
| SK | Sketch | General | Number prefix SK-01 for concept and RFI sketches issued outside the formal set – not for construction. |
| SL | Structural Level | Structural | Top of structure, excluding finishes. On architectural window schedules SL usually means Sill Level. |
| SOP | Setting Out Point | Survey | SOL = Setting Out Line. |
| SPEC | Specification | General | |
| SPT | Spigot | Mechanical | Spigot-and-socket pipe joint. On geotechnical borehole logs SPT is the Standard Penetration Test instead. |
| SQ | Square | General | Prefix form SQ 50 means 50 mm square section; AS 1100 also allows the square symbol before the size. |
| SS | Stainless Steel | General | |
| SSL | Structural Slab Level | Structural | Written SSL 24,300 (mm) or SSL 24.300 (m). FFL sits above SSL by the screed plus floor finish. |
| ST | Steel | Structural | Parts-list material column; AU hot-rolled grades are quoted to AS/NZS 3679.1, e.g. GR300 or 300PLUS. |
| STD | Standard | General | STD DET points to a reused detail from the office or authority library rather than one drawn for this job. |
| STRUCT | Structural | General | |
| SW | Switch | Electrical | On hydraulic and civil drawings SW is Stormwater, not Switch – check the discipline before reading it. |
| SYM | Symmetrical | General | Symmetrical about the centreline. |
T
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| T | Top | Structural | In reinforcement notes T and B are the top and bottom faces: N12-200 EW T&B. |
| T&G | Tongue and Groove | Architectural | |
| TB | Fully tensioned, bearing type (bolts) | Structural | Written 8.8/TB in AS 4100: bolt fully tensioned, but the joint is designed to slip into bearing. |
| TB | Tie Beam | Structural | Ground-beam tag on footing plans; distinct from the AS 4100 bolting category TB written as 8.8/TB. |
| TBC | To Be Confirmed | General | TBA = To Be Advised. |
| TBM | Temporary Bench Mark | Survey | |
| TEMP | Temperature | General | Also reads as Temporary on staging and site-works drawings (TEMP FENCE, TEMP PROP) – context decides. |
| TF | Fully tensioned, friction type (bolts) | Structural | Written 8.8/TF – no slip permitted, so faying surfaces must be masked or prepared, and the drawing must say so. |
| TFC | Taper Flange Channel | Structural | Written 100 TFC. Largely superseded in AU by PFC, so mostly seen on older drawings and existing steelwork. |
| THD | Thread | Mechanical | AU/UK callouts are metric: M12 x 1.75. US drawings write 1/2-13 UNC for the equivalent. |
| THK | Thick | General | Plate callouts read 10 THK PL; AU steel detailing more often compresses this to 10PL or PL10. |
| TOC | Top of Concrete | Structural | In the US also Top of Curb. |
| TOL | Tolerance | Mechanical | Undimensioned features usually rely on a blanket title-block call-up such as ISO 2768-1. |
| TOS | Top of Steel | Structural | Also used for Top of Slab. |
| TOW | Top of Wall | Structural | |
| TP | Tangent Point | Civil | Road and pipe setout – where a circular curve meets a straight; TP chainages are tabled in the alignment data. |
| TP | True Position | Mechanical | GD&T positional control; the frame reads position, Dia 0.2, M, A, B, and the located dimensions are boxed as basic. |
| TP | True Profile | Mechanical | The theoretical surface a profile tolerance zone straddles (ISO 1101 / ASME Y14.5), set by basic dimensions. |
| TR | Laundry Trough | Mechanical | AU fixture name; US sets say laundry tub or sink. On stair details TR usually means Tread. |
| TUN | Tundish | Mechanical | Open funnel taking relief-valve or tempering-valve discharge to drain; shown on hydraulic plans near the HWU. |
| TYP | Typical | General | The item repeats but is detailed once. TYP without a quantity is a classic RFI – confirm how many. |
U
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| U/S | Under Side | Structural | Soffit levels are written U/S SLAB RL 24.100; the matching top-of-member level is T/O or O/S. |
| UA | Unequal Angle (steel) | Structural | Written 150x90x10 UA, long leg first, to AS/NZS 3679.1. US equivalent notation is L6x4x3/8. |
| UB | Universal Beam (steel) | Structural | Written 310UB40.4 – nominal depth then mass per metre. US uses W-shapes (W12x26), UK uses UKB. |
| UC | Universal Column (steel) | Structural | Written 200UC59.5, to AS/NZS 3679.1. UK calls it UKC; US has no separate column series, just W-shapes. |
| UCUT | Undercut | Mechanical | Relief groove at a shoulder or thread root so the mating part seats fully. Also a weld defect name – context matters. |
| UG | Underground | General | Also written U/G. |
| UNO | Unless Noted Otherwise | General | Same force as UON; pick one form and keep it consistent across the whole drawing set. |
| UON | Unless Otherwise Noted | General | Attaches to general notes: “All bolts M20 8.8/S UON”. US sets usually write U.N.O. |
| uPVC | Unplasticized Polyvinyl Chloride | Mechanical | Rigid PVC pipe and window framing, now designated PVC-U. The u is unplasticised, not “UV-stabilised”. |
| uPVC | Unplasticised Poly Vinyl Chloride (PVC-U) | Mechanical | Modern designation is PVC-U, the grey DWV pipe. UV stabilisation is a separate additive. |
| UR | Urinal | Mechanical | Sanitary fixture tag – UR-1, UR-2 key back to the hydraulic fixture schedule. |
V
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| V | Volt | Electrical | |
| VAR | Varies or Variable | General | |
| VER | Vertical | General | VERT is the more common form on AU drawings; VER can be misread as version in file and revision names. |
| VERT | Vertical | General | Pairs with HORIZ in setout and reinforcement notes: VERT BARS N16-200 EF. |
| VOL | Volume | General | Concrete and earthworks quantities: m3 on AU/UK schedules, cubic yards on US ones. |
W
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| WAN | Wide Area Network | Electrical | Comms drawings show the WAN entry at the building MDF, with LAN distribution from there to floor racks. |
| WB | Welded Beam (steel) | Structural | On hydraulic drawings WB is a Wash Basin. On steel drawings 700WB115 is a plate-welded beam to AS/NZS 3679.2. |
| WC | Welded Column (steel) | Structural | Real collision: WC is Water Closet on architectural and hydraulic sets; 400WC144 is a welded column. |
| WC(P) | Water Closet With ‘P’ Trap | Mechanical | P trap discharges horizontally through the wall, so the drain setout sits above slab level. |
| WC(S) | Water Closet With ‘S’ Trap | Mechanical | S trap drops through the floor, so the slab penetration must be set out and cast in early. |
| WD | Working Drawing | General | Drawing-status label alongside DD (design) and AB (as built). On US architectural sets WD often means Wood. |
| WM | Washing Machine | Architectural | On hydraulic drawings WM commonly means Water Meter instead – read the discipline before assuming. |
| WT | Weight | General |
X
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| X | By. Example, “N12 x 1200 long” also means “N12 by 1200 long”. | General | Reads as “by” in sizes: 150x90x10 UA, 100x100x6 SHS. AU practice usually closes up the spaces. |
Y
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| YP | Yield Point | Structural | Older term; AU drawings quote the specified minimum yield stress fy instead, e.g. 300 or 350 MPa. |
Z
| Abbrev. | Meaning | Discipline | Notes |
|---|---|---|---|
| Z | Modulus of Section | Structural | Elastic section modulus in mm3 (Zx, Zy). AS 4100 uses Ze for the effective value and S for plastic. |
| Z | Z shaped steel purlin | Structural | Cold-formed to AS/NZS 4600, written Z20015 = 200 deep x 1.5 mm BMT. Z sections lap over supports; C sections butt. |
| Z | Zulu (Greenwich Mean Time) | General | UTC suffix on survey and site time records, e.g. 0930Z. AEST is UTC+10, AEDT UTC+11. |
Common questions
Where do I find the abbreviation legend on a drawing set?
On the front sheets. Most sets carry a legend, abbreviations and symbols sheet in the first few drawings, usually numbered 000 or A00. That legend overrides any general list, including this one.
What does FFL mean on a drawing?
Finished Floor Level — the level of the floor once all finishes are laid, written as a reduced level such as FFL 16,550. It differs from SSL, the structural slab level, by the thickness of the floor finishes.
What does NTS mean on a drawing?
Not To Scale. The detail is drawn for clarity rather than measurement, so you cannot scale dimensions off it. Work only from figured dimensions on an NTS detail.
What does TYP mean on a drawing?
Typical. The detail or dimension applies to all similar conditions, not just the one it points at. If it says TYP, expect it to repeat wherever the same situation occurs.
What is the difference between FFL, SSL and FGL?
FFL is the finished floor level including finishes; SSL is the structural slab level underneath them; FGL is the finished ground level outside the building. All three are reduced levels to the same datum.
Are drawing abbreviations standardised?
Partly. AS 1100 in Australia, ASME Y14.38 in the US and ISO 128 internationally cover many of them, but offices add their own. Always read the legend on the set in front of you.
About this list
Compiled by YZ in an Australian drawing office and maintained since 2004. First published 7 July 2004; revised November 2004, December 2005, August 2006, April 2020, May 2020 and July 2026. It now runs to 369 entries, which as far as we can tell makes it the longest such list published anywhere.
An acronym is formed from initial letters and pronounced as a word — CAD. An abbreviation is simply a shortened form — DIA for diameter. On drawings the distinction rarely matters; readability does. Only shorten a word when the full word will not fit, and keep to whatever your office legend already uses.