31 May
2003
31 May
'03
10:25 a.m.
That's it exactly. And your explanation was a lot more succinct than mine, too! Thanks.
I could be wrong, but I interpreted the OP's question to mean: is it possible to have the regex generate an error if more than one sub-field of a specific type is found, i.e. the following would be invalid:
~C123~C345
OK, negative forward lookahead asserts can be used for that: "~C\\d+(?!.*~C\\d)" John.