AIA & National CAD Standard Layer Format, Decoded

Last updated August 2, 2026

A-WALL-FULL-DIMS is not a code you have to memorise. It is four separate fields, each one a plain abbreviation, read left to right. Once you can see the fields, every layer name in a set of American drawings reads itself.

This is the AIA CAD Layer Format, which the United States National CAD Standard adopted and still carries. The standard itself costs money and is written for committees. The format underneath it is genuinely simple, and this page decodes it field by field with the full code tables.

The format

Field	Characters	Required?	What it says
Discipline designator	2	Yes	Who drew it. The second character is a hyphen or a user-defined modifier
Major group	4	Yes	The building system. No customisation permitted
Minor group	4	Optional	Narrows the major group. Limited customisation permitted
Second minor group	4	Optional	NCS long format only — see below
Status	1	Optional	Phase of work. Always the last field

The discipline code identifies the author of the graphic information, not the trade the object belongs to. That is the single most misunderstood rule in the whole standard: a structural column drawn by the architect is A-COLS, not S-COLS. It is how the same wall can legitimately appear as A-WALL in the architectural set and I-WALL in the interiors set.

Decoding A-WALL-FULL-DIMS

Field	Value	Means
Discipline	A	Architectural
Major group	WALL	Walls
Minor group	FULL	Full height
Second minor group	DIMS	Dimensions

A caveat worth knowing. That name has two minor groups, and the original AIA CAD Layer Guidelines define only one — in that version the fourth field is the status field, so A-WALL-FULL-DIMS would be reading DIMS as a status code, which it is not. The second minor group is part of the NCS long format, which lists four data fields as discipline designator, major group, two minor groups and status.

So if a layer name looks over-long against an older AIA chart, it is probably valid NCS rather than wrong. Both are below.

The same wall through the shorter forms

Layer name	Reads as
A-WALL	Architectural, walls. Major group only
A-WALL-FULL	Architectural, walls, full height
A-WALL-D	Architectural, walls, to be demolished. Status in the third field
A-WALL-FULL-D	Architectural, full-height walls, to be demolished. Status in the fourth
A-WALL-FULL-DIMS	Architectural, full-height walls, dimensions. NCS long format

Discipline designators

Code	Discipline	Code	Discipline
A	Architectural	C	Civil
E	Electrical	F	Fire Protection
G	General	H	Hazardous Materials
I	Interiors	L	Landscape
M	Mechanical	P	Plumbing
Q	Equipment	R	Resource
S	Structural	T	Telecommunications
X	Other	Z	Contractor / shop drawings

Status field

Code	Status	Code	Status
N	New work	E	Existing to remain
D	Existing to demolish	F	Future work
T	Temporary work	M	Items to be moved
R	Relocated items	X	Not in contract

A remodelling plan typically carries A-WALL-N for new walls, A-WALL-E for existing to remain and A-WALL-D for walls coming out — three layers, one system, freezable independently.

Major group codes

Four characters, mandatory, and no customisation is allowed. This is the field that makes files from different offices interchangeable, which is the entire point of the standard.

Code	Building system	Code	Building system
ABLT	Anchor bolt	ACCS	Access
ACID	Acid	ANNO	Annotation
AREA	Area	BEAM	Beam
BLDG	Building	BRIN	Brine systems
CABL	Cable	CHIM	Chimney
CLNG	Ceiling	CMPA	Compressed air systems
CO2S	CO2 systems	CODE	Code
COLS	Columns	COMM	Communications
CONT	Controls	CWTR	Chilled water
DECK	Floor decks	DETL	Detail
DOMW	Domestic water	DUST	Dust
ELEV	Elevation	ELHT	Electric heat
ENER	Energy management	EQPM	Equipment
EVAC	Evacuation	EXHS	Exhaust
FIRE	Fire	FIXT	Fixture
FLOR	Floor	FNDN	Foundation
FUEL	Fuel	FURN	Furniture
GLAZ	Glass	GRID	Grids
GRND	Grounding	HALN	Halon
HOTW	Hot water	HVAC	H.V.A.C.
IGAS	Inert gas	IRRG	Irrigation
JOIS	Joists	LGAS	Laboratory gas
LITE	Lighting	LTNG	Lightning protection
MACH	Machine shop	MDGS	Medical gas
METL	Miscellaneous metal	NGAS	Natural gas
NURS	Nursing	PGNG	Paging systems
PIPE	Pipe	PKNG	Parking
PLAN	Plans	PLNT	Plant
POWR	Power	PROC	Process
PROP	Property	PROT	Protection
RCOV	Recover	REFG	Refrigeration
RISR	Risers	ROAD	Road
ROOF	Roof	SANR	Sanitary
SECT	Sections	SERT	Security
SITE	Site	SLAB	Slabs
SOUN	Sound	SPCL	Special
SPRN	Sprinklers	STAN	Standpipe systems
STEM	Steam	STRM	Storm
TEST	Test	TOPO	Topography
TVAN	Television antenna	WALK	Walks
WALL	Walls	WATR	Water
XREF	External references

Minor group codes

Four characters, optional, and limited customisation is allowed. The published list runs to roughly 200 entries; these are the ones that come up daily. The full AIA CAD Layer Format PDF has the rest.

Code	Meaning	Code	Meaning
CNTR	Centre lines	DIMS	Dimensions
IDEN	Identification	KEYN	Key notes
LEGN	Schedule, legend, table border	NOTE	Notes
NPLT	Non-plotting information	OTLN	Outlines
PATT	Textures and hatch patterns	SYMB	Symbols
TEXT	Text	TTBL	Title blocks
FULL	Full height	PRHT	Partial height
PART	Partial height partition	MOVABLE	Movable
FIXD	Fixed	FREE	Freestanding
MOVE	Movable	EXTR	Exterior
INTR	Interior	FIRE	Fire wall
FH1H	One hour fire wall	FH2H	Two hour fire wall
HEAD	Door and window headers	JAMB	Door and window jambs
SILL	Sills	SWNG	Door swing arc
GLAZ	Glazing	CASE	Casework
STRS	Stairs, treads, escalators and ladders	HRAL	Stair and balcony handrails and guard rails
LEVL	Level changes, ramps, pits and depressions	OPEN	Ceiling and roof openings
SUSP	Suspended elements	RAIS	Raised
EDGE	Edge of slab	JOIN	Slab control joints
RBAR	Reinforcement	PILE	Piles, drilled piers
COLS	Columns	GRID	Grid
EQPM	Equipment	PFIX	Plumbing fixtures
APPL	Appliances	FURN	Furniture
PNLS	Furniture system panels	FILE	File cabinets
SIGN	Signage	ADAG	Disabled access guides
MCUT	Material cut by section	MBND	Material beyond section cut
ELEV	Elevations	PLAN	Plans
VPRT	Paper space viewports	ABAN	Abandoned
NICN	Not in contract	MISC	Miscellaneous

Annotation is the same in every discipline

Anything that is not a physical part of the building — text, dimensions, borders, detail references — goes in the ANNO major group. The same names are used whether the annotation sits in model space or paper space.

Layer	Contains
*-ANNO-DIMS	Dimensions
*-ANNO-KEYN	Keynotes
*-ANNO-LEGN	Legends and schedules
*-ANNO-NOTE	Notes
*-ANNO-NPLT	Construction lines, non-plotting information
*-ANNO-REDL	Redline
*-ANNO-REVS	Revisions
*-ANNO-SYMB	Symbols
*-ANNO-TEXT	Text
*-ANNO-TTLB	Border and title block

Dimensions, symbols and keynotes usually live in model space; legends, schedules, borders and title blocks in paper space. The layer names do not change between the two.

Elevations, sections and details

Each discipline gets its own groups for drawings that are not plans. The distinction between material cut by the section and material beyond it is what lets you give the cut line its own weight without touching anything else.

Layer	Contains
*-ELEV	Elevations
*-ELEV-IDEN	Component identification numbers
*-ELEV-OTLN	Building outlines
*-ELEV-PATT	Textures and hatch patterns with different pens
*-SECT	Sections
*-SECT-IDEN	Component identification numbers
*-SECT-MCUT	Material cut by section
*-SECT-MBND	Material beyond section cut
*-SECT-PATT	Textures and hatch patterns with different pens
*-DETL	Details
*-DETL-IDEN	Component identification numbers
*-DETL-MCUT	Material cut by section
*-DETL-MBND	Material beyond section cut
*-DETL-PATT	Textures and hatch patterns with different pens

Worked examples across the disciplines

Layer name	Reads as
A-DOOR-SWNG	Architectural · doors · swing arcs
A-FLOR-STRS	Architectural · floor · stairs and treads
A-WALL-FIRE	Architectural · walls · fire wall
S-COLS-GRID	Structural · columns · grid
S-SLAB-RBAR	Structural · slabs · reinforcement
S-BEAM-DIMS	Structural · beams · dimensions
M-HVAC-DUCT	Mechanical · HVAC · ductwork
P-PIPE-DOMW	Plumbing · pipe · domestic water
E-LITE-EMER	Electrical · lighting · emergency devices
E-POWR-PANL	Electrical · power · panels
F-SPRN-CLHD	Fire protection · sprinklers · ceiling heads
C-TOPO-SPOT	Civil · topography · spot levels
L-PLNT-GRND	Landscape · plants · ground covers
T-COMM-JACK	Telecommunications · communications · jacks
I-FURN-PNLS	Interiors · furniture · system panels
A-ANNO-TTLB-N	Architectural · annotation · title block · new

The other layer standard

The world runs two layer standards. AIA/NCS is used across North America and is a hierarchy of abbreviations: you read it like words. ISO 13567 is used across Europe and much of the rest of the world, and is a set of positional fields: you read it by counting characters.

	AIA / NCS	ISO 13567
Reads as	abbreviations	coded fields by position
Discipline	1–2 characters, letters (A, S)	2 characters, agent responsible
Element	4-character major group (WALL)	classification code, often from a national table
Learning curve	low — the name is legible	higher — you need the field map
Extension	user modifiers in the discipline and minor fields	designed-in optional fields
Used in	North America	Europe, Australia and elsewhere

If your office needs a third option, there is also the numbered layering system, which trades legibility for brevity.

The full format document

The AIA CAD Layer Format (PDF) — eight pages with the complete major and minor group listings, the annotation and view groups, and the methodology in full.

References

• The AIA CAD Layer Format — Methodology, the source for the field structure, discipline codes, status codes and the major and minor group listings on this page. draftsperson.net (PDF)
• United States National CAD Standard, CAD Layer Guidelines: Layer Name Format, published free by the NCS, for the long format’s two minor group fields and which fields are mandatory. nationalcadstandard.org
• United States National CAD Standard, overview and FAQs. nationalcadstandard.org
• ISO 13567 — CAD layer standard — the other half of the pair, field by field.
• Numbered CAD layering system — the shorthand alternative to both.