@TASCII[string]: Returns the number of 7-bit ASCII characters (0x00 - 0x7F) in string.
See also: @TALNUM, @TALPHA, @TCNTRL, @TDIGIT, @TLOWER, @TPRINT, @TPUNCT, @TSPACE, @TUPPER, and @TXDIGIT.
Examples:
echo %@tascii[abc]
3
echo %@tascii[abc 123]
7
echo %@tascii["abc"a]
5