Grooves are first cut across the spine, and then parallel to the spine, producing a shape something like that of an inverted T with a long bar and a very short stem. When done by machine, the slots may be punched through the leaves, thus eliminating the grooves. The latter method, however, makes it more difficult to insert the tapes through the slots. In the hand method, the grooves can be filled in with cord or other material after the tapes have been inserted.
Tape slotting is particularly suitable for large books printed on thin paper, e.g., unabridged dictionaries, encyclopedias, etc., which lack the margin required for side sewing. At times, two tapes are put through each slot for additional strength. (236 )