Over the years, AutoCAD has added and updated several system variables related to layers. Here's a list of a few notable ones, including the version it was introduced and when it was last updated according to the 2022 New AutoCAD Commands and System Variables Reference and 2023 Updated AutoCAD Commands and System Variables Reference:
The system variables for HPLAYER, DIMLAYER, CENTERLAYER, XREFLAYER, and TEXTLAYER have two options for the associated object type (hatch, dimensions, xrefs, and so on):
- . (a period) - This setting will place the object on the current layer.
- any other value - Any value other than a period will place the object on a layer based on the value of the system variable. If a layer by that name does not exist, it will be created.
The PDFIMPORTLAYERS system variable has options based on a value of 0, 1, or 2:
- 0 - AutoCAD checks the PDF for layers then creates corresponding layers with a PDF prefix for the imported PDF content. If no layers are found in the PDF, a setting value of 1 is used.
- 1 - AutoCAD checks what type of content is in the PDF and creates layers with a PDF prefix for the imported content such as PDF_Text and PDF_Geometry.
- 2 - AutoCAD will ignore all layer content in the PDF and import the content onto the current layer in the current drawing, even if layers with the PDF prefix already exist.
The PDFSHXLAYER system variable has options based on a value of 0 or 1:
- 0 - The text will be created on the same layer as the geometry being converted.
- 1 - The text will be created on the current layer.
The DIMCONTINUEMODE system variable has options based on a value of 0 or 1:
- 0 - The current dimension style and layer will be assigned.
- 1 - The dimension style and layer of the dimension being continued or used as a baseline will be assigned.
These settings can be set in the template or reset through other methods such as LISP.
