I've never been able to get a definitive answer on this; every source seems to be different, but most are somewhere around the information in Michael's link, i.e. you can temporarily disconnect a bayonet fitting, and then re-connect the same cooker. You can't leave it disconnected (reasonable enough because you can't be sure the fitting doesn't have a slow leak without checking for same). How long 'temporary' is, is not specified.
This has always been a problem in the Removal industry – some firms will cheerfully disconnect the cooker, others won't. For the firm I work with, I've now specified that we shouldn't touch them.