Then, you use Pat Match to compare a string to the pattern.
Pat Match returns True (1) if the pattern is found in the string, or it returns False (0) if the pattern was not found in the string.
For complete details, see the JSL Syntax Reference.
Constructs patterns that match the null string if the current position is int from the left end of the string, and fail otherwise.
Constructs patterns that match the null string if the current position is int from the right end of the string, and fails otherwise.
Constructs a pattern that matches forward to position int in the source string. It can match 0 or more characters. It fails if it would have to move backwards or beyond the end of the string.
Constructs a pattern that matches the null string and stores the current position in the source string into the specified JSL variable (varName). The assignment is immediate, and the variable can be used with expr() to affect the remainder of the match.
A simpler function, Regex (Regex), is also available. Regex returns a string value rather than a list, so Regex is usually easier to use in the Formula Editor than RegEx Match.