Concepts
Walkup checkin jobs are a special type of job applicable only to the kiosk interface. They are jobs which volunteers can sign in for without having a pre-defined assignment. Volunteers are still subject to the job requirements defined as part of the job itself. If the volunteer does not have, for example, a skill required by the job, he will not be allowed to sign in for it.
How to use
Use this to allow a large number of volunteers to check in for a special event or project without creating a job association or assignment for each and every volunteer. This can be useful when you have invited a number of people, but aren't sure who exactly will be showing up.