CAD tip # 7193:

You can create the layer list in Excel (CSV - comma-delimited values format), or type it in a text editor. The list can contain either the layer names only, or also their properties - color, linetype, lineweight, plot/noplot, visibility... Possible already existing layers will be redefined with the properties read from the CSV file.

The requested linetypes must be preloaded or they are autoloaded from the default .LIN file. Colors are supported both from the ACI palette (indexed) or as truecolors (specified as a "(R G B)" triplet). The parameters you don't want to set can be omitted.

You can download the application CsvLayers from Download. Load it with APPLOAD and type the CSVLAYERS command.

An example of the layer definition file:

  
;CsvLayers sample file
;Expected format:  
;LayerName[,Color#[,LineType[,NoPlot(0/1)[,Off(0/1)[,Freeze(0/1)[,Lweight#[,Description[,Transparency#]]]]]]]
;  
MyHidden,4,Dashed,1,1,1,25,"This will be hidden,OK?",50
YellowLayer,2,GAS  
GreenishLayer,(34 156 27)
Prague  
Ceske Budejovice,,,,,,,My hometown

The command LAYERS2CSV can export the CSV layer definition file from your existing drawing. You can then modify the list in Excel and re-import it to your AutoCAD DWG.

Enclose descriptions in double quotes ("") to include commas. You can preset your own delimiter by setting:

(setq _CSVdelimiter ";")