Panes

It is possible to collect Complete booklets and also Panes i.e. (the stamps without a cover attached) - so this category has been split into the two spheres.
Both the USA and Canada confuse the issue slightly by issuing panes that are complete booklets (e.g Sc2431a, Eagle and Shield) however these will be filed under panes - so check out both categories.
To compound the confusion, neither UNITRADE or SCOTT (and sometimes even STANLEY GIBBONS) actually recognise these as booklets and therefore do not allocate specific booklet numbers.

There is a significant catalogue premium for UNFOLDED Panes.