The oldest font format, and what the engine makes of it

Why a file has to carry its own fonts

A font is a file full of glyphs: one glyph per letter, per figure, per punctuation mark. Your computer holds a few hundred of them, and so does everybody else's — but not the same few hundred.

So a document that merely names the fonts it wants is a document at the mercy of the machine it is opened on. If that machine has never heard of the font, it puts something else in its place, the lines come out a different length, and the page you approved is not the page your customer reads.

The way out is to put the glyphs inside the document. That is what this engine does: the fonts travel with the file, and the file looks the same decades from now, on a machine nobody has bought yet.

The little identity card beside each font

Next to the glyphs, a PDF writes a few lines about the font: the name it goes by, how tall its letters climb and how far they drop below the line, whether they lean over, how thick a downstroke is. It is short, and every line of it is supposed to be true.

One line of that card is a set of boxes to tick. Two of those boxes matter here, and only one of the two may be ticked: this font writes ordinary words, or this font writes a set of signs — arrows, ornaments, mathematics, the sort of thing that is not an alphabet.

What that box is actually for — and what it is not for

That box changes nothing about what you see on the page. Not the shape of a letter, not the spacing, not the colour, not one dot of it.

It is read in one situation only: when the font is missing and the program has to invent a stand-in. Knowing whether it is standing in for an alphabet or for a set of arrows helps it invent a less embarrassing one.

And that situation cannot arise in a file this engine writes, because the font is inside the file. The box is therefore true or false the way a form is filled in correctly or carelessly — it costs nothing today, and it is the sort of thing a checker looks at.

Why the question comes up for these old fonts in particular

Adobe's first font format dates from 1990. It is still the format a print shop's older fonts are held in, which is why the engine reads it at all: a customer with three hundred fonts bought over twenty years should not have to throw them away.

A font in that format carries its own little table saying which number reaches which glyph — number 65 is the capital A, number 233 is the e with an accent, and so on. Some of these fonts carry a table of their own making. Others say, in effect, use the published table everybody already knows.

The published rules say what the box means; they do not settle either case. So we follow the only clue the font gives about itself, and that choice is ours.

The rule we chose

A font that brings a table of its own is written down as a font of signs. A font that points at the published table is written down as a font of ordinary words.

The reasoning is plain. Bringing your own table is exactly what a font does when it does not fit the ordinary alphabet — when number 65 is not a capital A but an arrow, an ornament or a company logo. Pointing at the published table is exactly what a font does when it is an ordinary alphabet. The rule follows the only clue the font itself gives us, instead of guessing from its name.

We could have ticked the same box every time and moved on. We did not, because a card that says the same thing about every font is a card that says nothing about any of them.

What we checked before choosing it

There is a standard for documents meant to be readable decades from now, and a free checker that says yes or no against it. That checker states every rule it applies, in writing, in a form we can read.

We read them before deciding. Exactly one rule ties this box to anything else: a font of signs must not also carry a table of its own. That looked like a problem, until the small print turned out to limit the rule to a different font format altogether. For the fonts on this page, neither answer breaks anything.

Then we checked the other way round: a document carrying one of these old fonts was put through the checker, and it passes. Not because we say so — because the checker says so, and it knows nothing about what wrote the file.

What it changes for you

One line of the identity card is filled in from what the font actually says about itself, rather than from a habit or a guess.

We are writing it here for the same reason we write down every figure our examples state: a decision you cannot see is a decision you cannot check. If you would rather we ticked the box differently for your files, that is a conversation, not a rewrite.

One more thing these fonts do differently

With every other kind of font, the engine travels light: only the letters your page actually draws go into the file. Write one word, carry one word's worth of glyphs.

A font in this old format travels whole, so the file is heavier. These fonts are locked in a way that makes them impossible to cut down: the lock is put on each glyph separately, so keeping a few letters and dropping the rest means unlocking the whole thing, rewriting its list of glyphs and locking it all again — while holding on to the strokes that several letters share, and to the letters built out of two others.

That is a piece of work of its own, and we have deliberately left it for a later version. Where it shows is a document of a few pages set in several of these old fonts: each one is carried whole, and the file can come out several times the weight of the same pages set in a modern font.

See it on a finished document

A page set in one of these fonts, stating what the font says about itself What makes a file readable decades from now The checker whose requirements we read before choosing

See the prices See the examples