Assume you have information in MyString and sure that USERID is there:
TempSting = SUBSTR(MyString, ATC('USERID', MyString)+LEN('USERID'))
Result = LEFT(TempSting, AT(' ', TempSting) - 1)

>I have a string that has ' USERID?? ' somewhere in the string. i want returned the characters directly after the USERID and before the next space or at end of string. 'the is USERIDABC code' I want ABC. 'The USERIDAA' I want AA.
>
>As always, I have a terrible time with string functions. Have been looking in my Help Character Function Favorites now for 30 minutes and only have a hodge podge of silly looking code.
>
>Thanks
>
>Brenda