Re: Font metrics in AFPDS?

["James H. H. Lampert" <jamesl@xxxxxxxxxxxxxxxxx>]

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