t_group type of raid set in DMRAID

Hello,

I'd like to know if the t_group type of raid set is mandatory or
optional if a group of disks can hold more than one raid sets, such as
ISW's volumes.

Also, I don't understand why "len2>len1" matters in the following
function in metadata.c. It screws up -s option usage for the ISW handler
as the group set name is smaller than that of a real raid set.

/*
 * Group RAID set(s)
 *
 *	name = NULL  : build all sets
 *	name = String: build just the one set
 */
static void want_set(struct lib_context *lc, struct raid_set *rs, char
*name)
{
	if (name) {
		size_t len1 = strlen(rs->name), len2 = strlen(name);

		if (len2 > len1 ||  /*(---ying questions this
condition!)*/
		    strncmp(rs->name, name, min(len1, len2))) {
			log_notice(lc, "dropping unwanted RAID set
\"%s\"",
				   rs->name);
			free_raid_set(lc, rs);
		}
	}
}


Thanks,
Ying