Senator Mark Pryor of Arkansas says members of the National Guard deserve more clarity about how long their tours of duty could take. An amendment Pryor co-sponsored would require the armed forces to be more explicit. It`s part of a bill that would authorize 87 (b) billion dollars for military operations and rebuilding in Iraq. Pryor says the amendment was offered after the Defense Department changed its policy on how deployments are calculated. He said that, in the past, when a unit was called up for a 12-month commitment, the clock began ticking when they reported to their local armory. But now, troops are not considered deployed until they arrive in the place they will be stationed, though they could be on active duty for months before and afterward.