The Support(s) command computes the characters present in the input string s, and returns a string consisting of these characters, each occurring once, in byte value order.

All of the StringTools package commands treat strings as (null-terminated) sequences of $8$-bit (ASCII) characters.  Thus, there is no support for multibyte character encodings, such as unicode encodings.

$\mathrm{with}\left(\mathrm{StringTools}\right)\:$

$\mathrm{Support}\left(''bacbaed''\right)$

$''abcde''$

$\mathrm{Support}\left(\mathrm{Random}\left(100000\,'\mathrm{lower}'\right)\right)$

$''abcdefghijklmnopqrstuvwxyz''$

$\mathrm{Support}\left(\mathrm{Random}\left(100000\,'\mathrm{dna}'\right)\right)$

$''ACGT''$