NRSI: Computers & Writing Systems
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Short URL: http://scripts.sil.org/FontFAQs
General Font FAQ
Questions on this page:
Question: Why can't you create a single font that contains all of the scripts needed rather than separate fonts for each script? Or, if you can't do it in one font, at least put all the IPA in each different writing system font.
- Building and testing an OpenType font for a single script such as Latin, Arabic or Hebrew is already a complex task; it's not just a collection of glyphs, but all the behavior involved. Attempting to combine these into a single font would add to the complexity of the build process and make it still more difficult to generate a correct, robust product. (You can't simply "append" one font to another; lots of internal tables would have to be merged.)
- Similarly, merging the actual outlines raises questions of design integrity (we don't have fonts for all the scripts mentioned that were designed together, to work harmoniously as a single typeface) and would mess up hinting (which depends on a bunch of font-wide parameters, which will conflict between the separate source fonts). And the result gives people less flexibility than if they apply distinct fonts for each script; this allows them to choose typefaces according to the particular project needs, rather than one predefined combination.
- This is essentially the standard (but naïve) request "I want a font that supports all of Unicode (so that I don't have to think about fonts any more)". There are limitations in the TrueType/OpenType font format that make this impossible, even apart from the fact that our development tools and processes would be overwhelmed.
- If we start down this road (e.g., combining Latin, Greek, and Arabic), there will be no end to the requests for additions - someone will want Chinese (already mentioned below), Ethiopic, Hebrew, Yi, Devanagari, Thai, you name it. How would we ever decide where to stop - and justify that decision to the vocal user whose favorite script didn't get included?
Our basic position is that this is the wrong approach to the issue. This is an application developer's problem. It is technically impossible with today's technology to create a single font that can display all the characters in Unicode, even if we wanted to. Applications need to deal with the fact that arbitrary text may require multiple fonts. (Today's operating systems provide fallback mechanisms to help with this, for cases where the app doesn't want to explicitly style all the text runs.)
Question: Will documents created with earlier (legacy) fonts such as the SIL IPA and IPA93 fonts be compatible with the new (Unicode) version?
Answer: No, documents which were created (encoded) with legacy fonts are not compatible with Unicode fonts. You will need to convert your data to Unicode. You can use TECkit for this process. We have mapping files (which work with TECkit) for converting documents which used our Greek, Hebrew and IPA fonts to Unicode. For instructions geared to IPA, see SIL IPA93 Data Conversion.
Question: Why is there an inversion of names? (eg SIL → Doulos SIL and SIL Charis → Charis SIL)
Answer: If SIL is in front of a font name then that probably means it is a legacy font. If it is after the font name it probably means it is Unicode.
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