The folding indexes are used in conjunction with the creep value setting. They specify how many times the creep is applied to each individual slot in a layout. This setup allows total flexibility in defining the creep for custom folds. Creep never applies to 1-up layouts, and is automatically calculated for 2-up layouts, so it can’t be defined for these layouts with less than 3 slots per sheet side.
The view shows either the index matrix for the front side of each
sheet, or for the back side of each sheet. The layout of the matrix
follows the layout of the columns and rows defined in the template,
and each slot in the matrix identifies the page index set for the slot
as defined in the page distribution of standard layouts. The
value input specifies the horizontal displacement factor, i.e. how
many times to apply the creep value to move the slot’s page inward
V value specifies how many times to apply the
creep value to move the slot’s page downward. Entering negative
values will reverse the displacement direction, allowing for the
creation of outward/upward moving creep.
The factory provided layouts come with folding indexes provided, so they will automatically do the right thing when creep is applicable. The easiest way to calculate creep for your own layouts is to create a dummy of the signature by printing a mockup of the layout and folding it as required for that particular layout. Then count for each page in the folded signature (= slot) its horizontal and vertical offsets within the fold (the index).
E.g. the first page in the folded signature is always on the outside, so it will have both a horizontal and a vertical index of 0. The second page, which is on the back side of the sheet at the same position has the same indexes. The other indexes will depend on the fold sequence. Generally for the usual four up layouts, which are folded twice, and thus after finishing have an outer and one inner sheet, the third page has a vertical index of 0 and a horizontal index of 1, because it is on the inner sheet. So, after folding a 4-up layout, all page indexes on the outer sheet (8, 1, 2 and 7) have folding indexes of (h:0, v:0) and all page indexes on the inner sheet (6, 3, 4, 5) have folding indexes of (h:1, v:0).