I’ve got two ideas to add to the pile:
1
Would it make more sense to group things across classes/years rather than isolate classes? Example:
10-19 Classes
11 Class meta/syllabi
11.01 Class 1 Syllabus
11.02 Class 2 Syllabus
12 Class notes
12.01 Class 1 notes
12.02 Class 2 notes
13 Big projects
13.01 Class 1 Project 1
13.02 Class 1 Project 2
13.03 Class 2 Project 1
This would also reduce the overhead of tracking individual class numbers, and make it so that all your recent projects are right there in front of you. I could see this being a limit if you have more than 100 big projects, but if that happens you could create another category or keep going at AC.100. I’ve never needed more than 7 IDs in a class, and most of those are the syllabus and notes. Considering only the big projects, I could easily fit them into 20-30 IDs across the 2 years I’ve had.
2
Since IDs can and should be big (22.00.0069: What is an ID?), if it’s possible to fit a class into 10 IDs, what about:
AS.CI:
Area
Semester
Class
ID
ex.
12.11 == Area 10 (classes), Semester 2, Class 1, ID 1
Keeps things vanilla-like and compact while still containing the same information as SX.C.ID, and can fit 9 classes a semester and 9 semesters (leaving 0 for meta) into a single area.