Computers & Writing Systems
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When to Convert to Unicode
Are there fonts available that will work for you?
Just having the characters you need in Unicode is not enough. Unicode is too big to fit all in one font, so you also have to find out which fonts contain all the characters you need. That is, all the characters you need for a particular language and script should be in the same font, and hopefully you’ll find more than one. If you use multiple languages or scripts, you can use a different font for each one.
There are some fonts that contain very large inventories of Unicode, plus many others that focus on specific scripts, so you’ve got a good chance of finding a font that will work. More are appearing every year. See Font Resources.
When you’re looking for a font, however, you need to consider more than just whether the font has the characters you need. For example:
- Smart behavior, in which the appearance of letters changes dynamically depending on context.
- Variant shapes of letters, such as “a” vs. “ɑ”.
- Overall appearance (serif vs. sans-serif vs. fixed-width, formal vs. informal, etc.)
- Licensing restrictions
- Special requirements for high-quality publication
Choosing a Font
- If you need any sort of smart behavior, such as correct positioning of diacritics, forming ligatures, changing the shape or position of a letter depending on its context, then you have to make sure that the font will provide that behavior in combination with your operating system and application software as discussed later in section Does available Unicode software meet your needs?.
- If you have preferences about the shapes of letters (such as “a” vs. “ɑ”), make sure all the shapes you want are available in the same font. (Sometimes font designers provide more than one shape for the same letter in one font, but you need special software in order to access anything other than the default letter shape.)
- You may have other requirements for the overall appearance of the font. For example, you may need a fixed-width font or a font suitable for new readers.
- Fonts sometimes have licensing restrictions that don’t allow you to do everything you might want with them. For example, you might be able to print with them on your own computer, but not transfer them to anyone else for them to view, print, or edit the files. The best choice is fonts that are covered by a license that grants you a lot of freedom, such as the Open Font License.
- Not every font works for high-quality publication. Appearance may be adequate for day-to-day work, but not meet the standards of your publisher. In particular, you will need a font family that has all four standard styles (regular, italic, bold, and bold italic). Application software or operating systems sometimes simulate bold and italic styles even if bold and italic fonts are not available. But, for high-quality publication, all four fonts are needed. This need not prevent switching to Unicode if you aren’t going to be doing any high-quality publishing in the next few years, but you should find out what options are being developed to meet your needs in the future.
- Some universities and publishing houses require their authors to use particular legacy fonts that are not Unicode-compatible, such as SIL’s IPA93 fonts (SIL IPA (Obsolete)). If you’re subject to such restrictions, you may have to either delay converting to Unicode or convert your data back to their specifications when you give it to them. (See section Are you willing and able to “straddle the fence”?.)
If you find that there are no fonts that meet your needs, you have these options:
- Abandon use of the feature that isn’t available. It may be more important to convert to Unicode than to retain some feature that is only supported by an older special character system.
- Convert to Unicode anyway and put up with the missing feature for a few years while you wait for fonts to support it.
- Work actively with font designers to implement the features you need.
- If our fonts do not quite meet your needs and if you are in SIL you may contact the NRSI for help.
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Provided by SIL's Writing Systems Technology team (formerly known as NRSI). Contact us here.