(Ian Hewerdine writes)
You’re correct, small caps is a character level marker like \nd and follows the same format: \sc …\sc*
I experimented with this today and found that PrintDraftChanges.txt allows me to modify non-marker text and insert markers. It does not allow me to remove or modify existing markers.
This isn’t mentioned in the Help files, so if one of the developers can confirm this behaviour, I’ll update Help to reflect this. The relevant Help topic is called: “How do I apply consistent changes to the text when creating output with Print Draft?”
Regarding markers, you can find all valid markers in the USFM documentation, which can be downloaded at: http://paratext.org/about/usfm