XUID field.

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XUID field.

Post by PJMiller » Wed Feb 22, 2017 10:30 pm

I have been told that Adobe products require a font to have an 'XUID' whatever that is. I have looked through the font properties and have not spotted this field.

What is an XUID field and what is it's significance ?

How is it used by programs?

Does a font generated by Font Creator have an XUID field ?

Is it generated by the program when the font is exported ?

If I modify the font will it get a new XUID or does it get one at the start and keep the same one whatever happens to the font subsequently ?

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Re: XUID field.

Post by MikeW » Wed Feb 22, 2017 11:05 pm

From: Thomas Phinney of Adobe
Subject: [OpenType] Why you don't need UniqueIDs
Date: Fri, 04 Mar 2005 10:04:41 -0800
Neither Type 1 nor OpenType CFF fonts require PostScript UniqueIDs.

Back in the mid-80s, when printing might be done on a 57K serial connection and printers might have 8 MHz processors, the caching of device-generated bitmaps enabled by UniqueIDs made a noticeable speed difference. With today's connection bandwidths and printers, the printing speed difference was insignificant in our tests (conducted around 2002), and certainly not enough to outweigh the risks of collisions between UniqueIDs for different fonts and the trouble of tracking the ID numbers.

For these reasons, Adobe stopped using UniqueIDs (and XUIDs) in our own OpenType CFF fonts. If we still made Type 1 fonts, we wouldn't use UniqueIDs for them, either.

You may of course continue to use UniqueIDs, it's just that they are not necessary.



Thomas W. Phinney
Program Manager
Fonts & Core Technologies
Adobe Systems

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