\mathscr - Used to turn on script typestyle for uppercase letters. If lowercase script letters are not available, then they are typeset in a roman typestyle.
{ \mathscr #1 }
\mathscr command is used to turn on script typestyle for uppercase letters. If lowercase script letters are not available, then they are typeset in a roman typestyle.
\mathscr{ABCDEFGHIJKLMNOPQRSTUVWXYZ}
\mathscr{0123456789}
\mathscr{abcdefghijklmnopqrstuvwxyz}
abcdefghijklmnopqrstuvwxyz
\mathscr{AB}AB