Expand a heading's number list into the individual numbers it covers.
2 und 3 -> ["2","3"]; 4 bis 6 -> ["4","5","6"]; 1 a -> ["1a"].
A letter alone names a sub-item of the lettered number before it: 8 a und b ->
["8a","8b"], 9 a bis c -> ["9a","9b","9c"]; after a number without a letter it
names nothing, and is dropped.
A range is only expanded when both ends are plain integers and the span is small;
a "range" of 40 numbers is far more likely to be a misread than a real grouping,
and expanding it would fabricate 40 question numbers.
Expand a heading's number list into the individual numbers it covers.
2 und 3-> ["2","3"];4 bis 6-> ["4","5","6"];1 a-> ["1a"]. A letter alone names a sub-item of the lettered number before it:8 a und b-> ["8a","8b"],9 a bis c-> ["9a","9b","9c"]; after a number without a letter it names nothing, and is dropped.A range is only expanded when both ends are plain integers and the span is small; a "range" of 40 numbers is far more likely to be a misread than a real grouping, and expanding it would fabricate 40 question numbers.