A variable OpenType font can draw its glyphs with CFF2 charstrings, whose operands carry deltas (blend) that are scaled by how far the requested location lies inside each region of the design space. The glyphs below are drawn from one such font at different weights and widths. In the PDF each location is embedded as a static CFF font, because PDF cannot embed a variable one.
ABCDEF font-weight: 100 | ABCDEF font-weight: 400 |
ABCDEF font-weight: 700 | ABCDEF font-weight: 900 |
ABCDEF font-stretch: semi-condensed (75%) | ABCDEF font-stretch: semi-expanded (125%) |
ABCDEF 'wght' 250 | ABCDEF 'wght' 650, 'wdth' 110 |