──VERIFY(string,reference─┬──────────────────────────┬─)────
└─,─┬─────────┬─┬────────┬─┘
└─option──┘ └─,start─┘
VERIFY returns a number indicating whether string is composed only of characters from reference. VERIFY returns the position of the first character in string that is not also in reference. If all the characters were found in reference, 0 is returned.
The third argument, option, can be any expression that results in a string starting with N or M that represents either Nomatch (the default) or Match.. Only the first character of option is significant and it can be in uppercase or lowercase, as usual. If Nomatch is specified, the position of the first character in string that is not also in reference is returned. 0 is returned if all characters in string were found in reference. If Match is specified, the position of the first character in string that is in reference is returned, or 0 is returned if none of the characters were found.
The default for start is 1, thus, the search starts at the first character of string. You can override this by specifying a different start point, which must be a positive whole number.
VERIFY always returns 0 if string is null or if start is greater than LENGTH(string). If reference is null, VERIFY returns 0 if you specify Match; otherwise, 1 is returned.
Here are some examples:
VERIFY('123','1234567890') -> 0
VERIFY('1Z3','1234567890') -> 2
VERIFY('AB4T','1234567890') -> 1
VERIFY('AB4T','1234567890','M') -> 3
VERIFY('AB4T','1234567890','N') -> 1
VERIFY('1P3Q4','1234567890',,3) -> 4
VERIFY('AB3CD5','1234567890','M',4) -> 6