Wildmatch() is used to compare strings. The wildmatch function performs a case insensitive comparison and permits the use of wildcard characters ( * and ?) in the comparison strings.
* is used for multiple characters
? is used for single character
Example:
wildmatch( M, 'ja*','fe?','mar') // In this 'ja*', the first two characters should be ja Or JA, for 'fe?' the first 2 characters should be fe and third character should be of any character.
returns 1 if M = January
returns 2 if M = fex
You can try all this by pasting the expression using Text box object.