The counter, prefixes and suffixes

Every value Increment writes is built the same way:

prefix + counter + suffix

The counter is the part that changes from object to object. The prefix and suffix are the text that surrounds it.

The Counter and Value sections of the MD Increment window: counter style, start, step and digits above the prefix and suffix boxes, with the target scope set to attributes only and the attribute set to TERM.

The counter

Style	Renders	Zero padding	Case
Number	`1, 2, 3`: a negative puts its sign before the padding (`-007`)	yes	-
Letter	`A … Z, AA, AB`	-	yes

Three fields shape a run:

Start: the first value. 101 starts at 101; with the letter style, 1 is A.
Step: added per object. It may be negative to count down, or 0 to write the same value everywhere.
Digits: how many characters to pad the number to, minimum 1. 3 gives 007, then 042, which is what makes a column of numbers line up. Padding does not apply to letters, so the box is greyed rather than ignoring you.

Letters are bijective base 26: 1 is A, 26 is Z, 27 is AA, 702 is ZZ. There is no zero, so the ladder never produces the BA that a naive base-26 count gives at 27.

Prefixes and suffixes

Type them and they are written literally. P- as a prefix and a counter starting at 101 gives P-101, P-102, P-103.

Anything can go in either box: a discipline code, a sheet number, a space, a dash. The counter sits between them.