Hi Richard
ST does have some Regex functionality but I had not thought of these new Character Range methods (introduced in version 3.70) in that light. I guess you could think of the character ranges as either having been borrowed from regex or alternatively implementing a very small subset of regex, but really it was just an abbreviation as I found typing out all the characters tedious and potentially error-prone and the alternative of writing a loop dealing with one character at a time seemed less than ideal.
I see you have started another thread which is a good idea as we are having thread drift here and being off-topic so I will answer over there instead: