DWG files come in two flavors. One uses traditional CTB (color based plot tables), the other uses STB (style based plot tables). Plot style is a general property that can be assigned to an object or a layer in the STB “flavored” DWG file. An object can also inherit this property from a layer much like color, linetype or lineweight when set to ByLayer.
In DWG file of CTB flavor, the plot style property is set to ByColor and cannot be changed.
If PSTYLEPOLICY (a variable saved in the registry) is set to 1, new files (unless created from templates) will be CTB flavor of DWG and will use CTB for plotting; when it is set to 0, new files will be STB flavor of DWG and will use STB for plotting.
When you need to convert DWG files from STB flavor to CTB flavor, you need to strip the plot style property from the objects and layer definitions. This can be done easily using the following script. DWG files of CTB flavor will not be affected by this script.
CONVERTPSTYLES QSAVE Blank Line
When you need to convert from CTB to STB, you need to add that property to the objects and layer definitions.
Before converting a CTB flavor of DWG file to STB flavor of DWG file, you first need to have a STB table which you will be able to use with your former CTB DWG file.
To accomplish this, type CONVERTCTB at the command line and select the CTB to be converted to STB. IN this example, I selected ACAD.CTB to be converted to ACAD2.STB
You can then use the following script to batch convert CTB DWG files to use ACAD2.STB. DWG files of STB flavor will not be affected by this script.
CONVERTPSTYLES ACAD2.STB QSAVE Blank Line
Note: Files that were using STB, when converted to CTB usually plot best with the Monochrome.ctb pen table. For color and grayscale output, use true colors.