Open schedule jobs are jobs that volunteers can sign up for via VSys Live but which do not generate real assignments. Instead they're used for things like "We need an intern" or "Technical help wanted". Use this to recruit skills based volunteers.
These jobs can be searched using the job signup tool in VSys Live. Once a volunteer signs up for an open schedule job he gets an assignment for the underlying job. That assignment has a blank Start date so you can find those assignments and handle them manually by contacting the volunteer to determine eligibility and possibly create a schedule of real assignments.