Hi David,
What do you have set for the following dcadwin.ini values? Having PurgeDrawingsOnExit=1 will have Datacad look at the (Automatic) entries below and then purge out each type when closing a drawing and choosing to save your changes. It does not work if you force save the file using F & then close and choose to not save. This will purge out items of each type so your drawing is not lugging around things it may not need anymore. The (Manual) lines are for when you use the File, Purge option and the default settings for the utility. Below is how I have mine set which purges out everything except empty layers since our base files have empty layers in the, for future use.
[General]
PurgeDrawingsOnExit=1
[Purge]
HatchPatterns(Automatic)=True
HatchPatterns(Manual)=True
Layers(Automatic)=FALSE
Layers(Manual)=True
LineTypes(Automatic)=True
LineTypes(Manual)=True
Materials(Automatic)=True
Materials(Manual)=True
Show Layers(Manual)=False
Show Symbols(Manual)=False
Styles(Automatic)=True
Styles(Manual)=True
Symbols(Automatic)=True
Symbols(Manual)=True
I don't recall what these lines do though. Hmmmm
Show Layers(Manual)=False
Show Symbols(Manual)=False