It finds as many repetitions as possible. This is used to suppress the special meaning of a character when matching. As in arithmetic, parentheses can change how operators are grouped. There are two other alternatives that you might prefer. To do this, you must use character sets or tolower .
Case is always significant in compatibility mode.
Comparison Expressions as Patterns Comparison patterns test relationships such as equality between two strings or numbers. True if x is less than or equal to y . True if x is greater than or equal to y . True if x is equal to y . True if x is not equal to y .