Hi, Mike,
I would not dignify my dabbling on the fringes of philately with the appellation 'research', or even investigation - I was just curious.
I take your point about the sheets for booklet panes being produced separately from 'counter sheets', but some varieties which (afaik) appear only on stamps from booklets are catalogued, others are not, and I wondered whether anyone knew if there was a reason behind this.
Thanks for your input, anyway - as for criticising SG, if we do that, don't we have our tweezers confiscated ?
T