@ISPUNCT[string]: Returns 1 if string is entirely composed of punctuation characters, i.e. printable characters which are not alphanumeric or space; 0 otherwise.
See also: @ISALNUM, @ISALPHA, @ISASCII, @ISCNTRL, @ISDIGIT, @ISPRINT, @ISSPACE, @ISXDIGIT.
Examples:
echo %@ispunct[.]
1
echo %@ispunct[+]
1
echo %@ispunct[:-)]
1
echo %@ispunct[.,a]
0