/**
* Check the filter command line options.
*
- * \param fa The command line options.
+ * \param fa The filter argument.
* \param conf Points to the filter configuration upon successful return.
*
- * Check if \a fa starts with a the name of a supported filter, followed by
- * a colon. If yes, call the command line parser of that filter.
+ * Check if the given filter argument starts with the name of a supported
+ * filter, optionally followed by options for this filter. If yes, call the
+ * command line parser of that filter.
*
* \return On success, the number of the filter is returned and \a conf
* is initialized to point to the filter configuration determined by \a fa.