Synopsis:
\usebox{box-cmd}
Produce the box most recently saved in the box register box-cmd by the commands \sbox or \savebox, or the lrbox environment. See \sbox & \savebox, for more information and examples. (Note that the variable name box-cmd starts with a backslash, \.) This command is robust (see \protect).
© 2007–2018 Karl Berry
Public Domain Software
http://latexref.xyz/_005cusebox.html