In the documentation for Page Layout Editor (the tool used to modify worksheet templates) it claims that the user can define and use interpolation variables (aka “format” variables for some reason) for comments %C0 thru %C9 (http://docs.kicad.org/5.0.0/en/pl_editor.html#format-symbols)
However, in the eeschema dialog for menu item File|Page Settings… There are only 4 comment lines and no obvious way to add or modify these variables in the dialog. I was digging thru the code and got as far finding the menu item triggers ID_SHEET_SET, which links to EDA_DRAW_FRAME::Process_PageSettings in the dispatch table of sch_edit_frame.cpp. At that point I decided to see if anyone on the forum knows anything about this.
I’m guessing that this is all just hard coded in ::Process_PageSettings but maybe someone else knows already without me burning a half day digging. (@bobc ?)
Thanks in advance for not replying with guesses, unrelated questions, or hijacking my question with some other discussion.
You will also need to add event callbacks and resources for each new variable or comment, remember to update the constructor and destructor and probably eat some worms.
So essentially there is no user method available to use comments %C0, %C5-%C9 or to use variables for tracking revisions, approvals, patent notices.
Fair enough, that is the answer for 5.0.0 at least.