declaration/definition
save-clear shelf-name
save-clear is the equivalent of a save declaration followed immediately by
a clear action.
Because the size of the shelf is changed using a save-clear declaration, it may only be used on
shelves that are declared to be variable. save-clear declarations may not have attached
conditions. Unlike the save declaration, when save-clear is applied to stream
shelves, there are no restrictions on what the items may be attached to.