I have a drawing register that lists drawing numbers and the last time it was
issued. Initially the drawing is issued with a numbers, however as the
project continues, the number changes to a letter, eg A, then B, C etc. If
the drg has been issued as a number I want to extract the largest number,
however if its a letter, then i want to find the latest letter eg

a particular drg may be issued
S1001 1 2 3 4 5 A B C so i want to be able to extract C
S1002 1 2 3 so i want to be able to extract 3
S1003 A B C D E so i want to be able to extract E

its ok if there are only a couple of drawings, but 500+ drgs takes a while
to sort out