Ascii package NBSP and NUL symbols

Question

The following does not work:

\documentclass{standalone}
\usepackage{ascii}

\begin{document}
$\NBSP$
$\NUL$
\end{document}

The error under pdflatex and xelatex is

Undefined control sequence \NBSP
Undefined control sequence \NUL

The symbols \NBSP and \NUL are listed by the Latex Comprehensive Symbol List (LCSL), but there seem to be no trace of these symbols in either the ascii package documentation, or in the ascii.sty style file (MikTeX 2.9).

Which symbols is LCSL showing?

Answer 1

The definition of \NBSP is

% ascii.sty, line 90:
\def\NBSP{{\asciifamily\char"A0}\xspace}

and this implies that \NBSP will definitely not work in math mode. Indeed, if you try it, you'll see, in the .log file

Missing character: There is no <A0> in font cmr10!

Without $'s it works:

\documentclass{standalone}
\usepackage{ascii}

\begin{document}
\NBSP
\NUL
\end{document}