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Re: [Groff] Goofy spacing in devps

From: Alejandro Lopez-Valencia
Subject: Re: [Groff] Goofy spacing in devps
Date: Wed, 23 Apr 2003 21:00:40 -0500

At 04:13 p.m. 23/04/2003, Timothy Groves wrote:
Not knowing much about typesetting, I do not know what kerning and
ligature is.  My letters tend to run together, or be spaced out too far.
It occurs consistently;  certain words are mangled the same every time.
The condition appears to be independant of font;  I have tried using
three different fonts, and get identical results;  the words are mangled
exactly the same way in Helvetica as they are in Courier.

Hmmm... Perhaps you are using an oldish groff release? I'd recommend that you obtain a CVS snapshot (from and try with it. The font metrics are *much improved* to whatever you may find in any prepackaged binary distribution. You'll need byacc or a CVS snapshot of Bison (nothing older will be able to process the current groff sources).

On kerning and ligatures... <inhale>

A ligature is an old typographical device that tries to imitate the handwriting custom of substituting several characters by one that is a mix of the original or a shorter, different one. Ligatures are as old as the written language and they evolved in some languages such as Sanskrit, Devanagari, Hindi, Hebrew and Arabic among others to be integral part of the written language (the so called "presentation forms" that vary depending on their position in the word and even in the sentence. Hebrew has the simpler system of the examples I mention above). In the West, ligatures were an art practiced by copyist monks in Medieval monasteries, and they were introduced to metal typesetting by Guttenberg himself in his 42-line bible. The typeface he designed for printing this book had more than 200 different ligatures! Nowadays most typefaces used for digital typesetting (as in Type 1 fonts sold by Adobe and other big foundries) contain only three ligatures: fi, fl and & (an old ligature for "et cetera", latin for "and so on"); btw the German eszet is a letter on its own although historically *was* a ligature. Older non-digital typefaces, as say phototypesetter designs that used to come in film and would be "projected" onto light sensitive plastic sheets would include other ligatures such as fff ffl, ffi and even fj and ct. In summary, ligatures are an old and fancy way to write abbreviations.

Kerning is a term that describes the adjustments on horizontal advance width between character pairs that would otherwise have too tight or loose a spacing between them, Two classic examples: AV and AO. The idea is to obtain an uniform "color" or "grayness" in the printed page, instead of text with running "rivers" of white space. If you try to do this with three or more characters it is called tracking and, btw, you can do it with groff, by hand. :-) BTW, kerning and overall spacing depend very much on the typeface design. Fixed width, aka monospaced, typefaces such as Courier, obviously have no kerning, and others such as Helvetica were designed such that the ligatures have the same spacing as the individual characters placed together.


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