 Typesetting glue order

A typesetting glue order assigns a priority to stretch or shrink in TeX. The orders are normal finite flexibility, fil, fill and filll, in increasing priority. With nonnegative coefficients, the highest present order absorbs the adjustment; lower-order flexibility is left unused.^[ref]

For example, suppose a line has natural width 22 and must reach width 34. Two zero-width glue items have stretch coefficients 1fil and 2fil. Their added widths areA finite-order glue item in the same line keeps its nominal width during this adjustment. The symbols define priorities for distributing a finite width difference. Within the selected order, the coefficients still determine proportional sharing.

The simple finite model in typesetting glue uses only the normal order. Higher orders make it possible to place flexible space at selected locations, such as before or after a line's content, without requiring the ordinary word spacing to absorb that particular adjustment.