See the documentation at for the autocad_resolved_linetype attribtue: https://docs.safe.com/fme/html/FME_Desktop_Documentation/FME_ReadersWriters/acad/Feature_Representation.htm#autocad_resolved_linetype

On the featuretype, click the cogwheel, format attributes, and filter on resolved. You can expose it by checking the box in front.

Thanks @tomvanderputte i am already exposing that attribute but am trying to find out the actual definition of the line in more detail if it is not a solid line. For example if the line was a dash and then a dot, what are the spacing of the line, so i can try and recreate on output.

If you have AutoCAD installed on your computer you can look in the folder C:\\Users\\<user_name>\\AppData\\Roaming\\Autodesk\\<autocad_version>\\<build>\\<language>\\support

There you can find .lin files that looks like this:

ACAD_ISO02W100,ISO dash __ __ __ __ __ __ __ __ __ __ __ __ __

Thanks @gabriel_hirsch, that is good to know but what I am trying to do is validate that a drawing supplied by an external party has the correct line definition. I can test that the line type has the correct name but can't figure out how to test that the line definition is correct.

OK, can't help you there I'm afraid.