Note that the incrementation sequences are
0..9 => 0 + carry|1 i.e 10
A..Z => A + carry|A i.e. AA
a..z => a + carry|a i.e aa
- bz => ca
- wrapping the z->a gives a carry to the b next in Lower a..z is c.
- Zz => AAa
- wrapping the z->a gives a carry to the Z next in Upper case A..Z is AA.
- z9 => aa0
- incrementing 9 wraps round to zero, passing a carry up to the z. Next up from z is aa
- 9z => 10
- tricked you!! - string autoincrement only works on patterns matching regex /^[a-zA-Z]*[0-9]*\z/, this doesn't match that pattern, so treats leading number(s) as the (numeric?) value and increments that. 9 goes to 10 :-)
If you spot any bugs in my solutions, it's because I've deliberately left them in as an exercise for the reader! :-)
