Help with code to extract some text

Hi everyone,

The WBS element Medium Description has some text that we would like to extract and load into a new infoobject called ZBUDREF. For example:

The description is "WBS T808". We always want to start reading from the last character of the text (so the number 8) and keep on reading till we encounter a letter (in this case the letter T). Once we hit T, we want to extract T808 and that is what will be loaded into ZBUDREF.

Can someone please help me with the code? I think it's quite simple but I'm not good with ABAP (yet). Please advise the best strategy of employong the code if you can, meaning where the code will be written (transformations, Start Routine, End Routine?). I would highly appreciate the help.

Thanks in advance!