OpenType
OpenType is the wider shape a typeface file comes in: the letters, and the typographic refinements that go with them.
In more detail
A typeface is more than a row of letters. It knows that certain pairs sit too far apart and want closing up, that two letters sometimes want to be drawn as one, that figures can be set to line up in a column or to rise and fall like lowercase letters. All of that is written into the file beside the drawings.
The format takes either kind of letter drawing, which is why a typeface bought today usually works everywhere without anybody having to think about which kind it holds.
What it does on a real document
The refinements are not applied by accident: a document asks for the ones it wants, and the same text can be set with them and without, side by side, from the same file.
The file itself travels inside the document, so a reader who has never had the typeface still sees the refinements exactly as they were asked for.
Where it comes from, and why
It was agreed in the mid nineteen nineties by two firms that had each been pushing a format of their own, and it was built to take both rather than replace either.
The refinements came from the trade: a typesetter had always done them by hand, and putting them in the file let a machine do them the same way every time.
See it on a finished document
The rules behind this word, and the texts they are read from
Glossary
- font
- The drawing of every letter, digit and mark a document writes, held in a file of its own. A PDF carries the fonts it is set in inside itself, which is why it opens looking the same on a machine that has never had them. Leave them out and a reader puts another font in their place, and the layout moves.