Re: Font metrics in AFPDS?

On 3/18/15 4:50 PM, Booth Martin wrote:

"Kern" may be the word you are looking for?

A kern is a portion of one glyph that overlaps an adjacent character position.

In foundry type, a kern is a physical extension of the letter past the left or right side of the type body. And if it collides with part of an adjacent letter, it will break off. That's why the ff, fi, fl, ffi, and ffl ligatures are by far the most common: they don't just save some miniscule amount of the typesetter's time; they also allow the component letters to be set in a way that's visually right, without breaking the type.

In linecast type, except for the above ligatures, kerning is only possible on a Ludlow, and only with oblique matrix bodies. That's why italics tend to look a little loose when set on a Linotype or Intertype.

In phototype and digital type, of course, kerning (and tracking adjustments) can be done with reckless abandon, since you're not trying to put two physical objects into the same space, nor are you (were you to attempt loose tracking without inserting spacing material) opening up gaps that would leak hot type metal (as on linecasting equipment) or keep the type forme from lifting (as in foundry type or Monotype).

But getting back to width tables and measuring the set width of type:

I actually have manually generated width tables (for Postscript fonts that I wanted to use in Xerox Ventura Publisher, but for which there weren't any compatible width tables), and well, there are only 190 characters to deal with in EBCDIC, and around 50 of them are just diacritical variations on others, so it wouldn't be all that difficult to do it myself. But if somebody else has already invented that wheel (and at some level, somebody HAS to have, in order for the fonts to be usable), it's a shame to have to reinvent it myself.

--
JHHL