Opening a can of worms

[K. Berry]

    PS: Shouldn't it read `must not' instead of `may not' in the first
    two items in section 2.2.2?

The two items in question are:

    {\abbr{ISO}-9660} imposes the following limitations:

    \item File and directory names, not including any directory path or
    extension part, may not exceed eight characters.

    \item Filenames may have a single extension.  Extensions may not exceed
    three characters. Directory names may not have an extension.

In this case, I find `may not' preferable to `must not' or `shall not'
for some reason. I know it's ambiguous, though. I'll change it if others
prefer, I don't feel that strongly.