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Layer Tool LISP: Process AutoCAD Layers by Picking Objects

September 19, 2020

Last updated July 28, 2026

Layer Tool bundles the everyday layer operations into one command driven entirely by picking objects. Set the current layer, turn layers off, move objects to another layer, and build up a working list of layers as you go — all by clicking on things rather than reading names out of a dialog.

It is by Axsys Technology Ltd, copyright 1990 to 1993 — the same house that wrote the distance and bearing labeller and the polyline joiner on this site.

The options

The documentation lists them, and the shape of the tool is clear from the list: everything works from a selection rather than a name.

  • Set — make a layer current by selecting something on it.
  • Off — turn layers off by selecting objects on them.
  • Add — add layers to the current list by selecting objects.
  • Del — remove layers from that list the same way.
  • Move — move selected objects onto a layer.

The list is the interesting part. Add and Del do not touch the drawing — they maintain a set of layer names that the tool remembers, which the other options then work against. So you can build up a group of layers by pointing at examples of each, and then operate on the whole group.

That list is stored in a file with a .LYR extension, so it survives between sessions. The documentation notes it can also be created and manipulated by a companion program called FIG.LSP, which is not in this download.

The command name is a poor choice today

The command is LT. In 1990 that was a sensible abbreviation for Layer Tool. It has aged badly for two reasons.

The obvious one is that LT now means AutoCAD LT to every drafter alive, so anyone reading your setup will misread it. The practical one is that two letters is prime alias territory — check it against your own shortcuts before loading, because the collision will be silent.

Renaming it is a one-word edit at the top of the file, and worth doing.

It comes with its own help screen

A period detail worth knowing about. The archive contains a .DOC file that is plain text, not a Word document, and the routine can display it on screen a page at a time with a “Press ENTER to continue..” prompt between pages.

That was how you shipped help before dialog boxes were common, and it still works — the file has to be findable on AutoCAD’s support path for the help option to locate it. If the help screen reports that it cannot find the file, that is why.

How to load it

The download is called PLAY.zip but the files inside are LT.LSP and LT.DOC — do not go looking for anything named play. Put both in one folder on the support file search path, then load the LSP with APPLOAD. Our AutoLISP guide covers loading and the search path.

Step-by-step usage

  1. Type the command — LT as supplied, or whatever you renamed it to.
  2. Choose an option: Set, Off, Add, Del or Move.
  3. Select objects to identify the layers you mean.
  4. Use the help option if the prompts are unclear — it displays the full documentation on screen.

Try Set and Add first, since neither changes the drawing. Off and Move do, so save before experimenting with those.

Compatibility notes

1990 to 1993, so written-for rather than tested-on. It reads and writes its own data file and drives the LAYER command, both of which are stable ground, though the file handling is the part most worth testing first.

Plain AutoLISP with no dialog boxes and no Express Tools calls, so nothing requires the full product; LT users on LT 2024 or later, the release that brought AutoLISP to LT, should be able to run it — which is a sentence that reads oddly given the command name. See what runs on AutoCAD LT.

Download

Name: Process Layer
Description: Program to process layers quickly based on object selection.
Type: AutoCAD AutoLISP Routine
Author: AXSYS
File Size: 3 Kb
Cost: Free
Worked on: AutoCAD
Download File: PLAY.zip

Related routines

  • LayerMatch — just the Set operation, and it reads inside blocks.
  • LS — set a layer or create one on the fly.
  • Delete Layer — strip a layer out entirely.

References

  • AutoLISP: the complete guide
  • Free LISP routines library
  • AutoLISP on AutoCAD LT

Filed Under: AutoLISP Routines

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