Commands can have more than one argument.  If just one argument is
expected, any embedded `,' characters are ignored, like in `sample1,
sample2'.  Otherwise, the `,' is interpreted as an argument separator.
For example, the @uref command can have up to three arguments: `URL',
TEXT (URL), or REPLACEMENT.  Additional `,' are considered part of the
last argument, but are removed: REPLACEMENT1 REPLACEMENT2.

