A generic FAQ for all of our Roman fonts can be found here: Latin, Cyrillic, and Greek Fonts – FAQ. FAQ’s specific to Doulos SIL are found below.
What characters are included with this release?
See Character Set Support for the full listing.
Why is there an inversion of names? (eg SIL Doulos -> Doulos SIL)
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.
Why does the font have some Greek characters, but not all?
While it is true that the font includes some Greek characters, it is not intended to provide general support for the Greek language. Those Greek characters that were included were done so in order to support various (primarily linguistic) notational systems. If Greek language support is needed, the Galatia SIL and Gentium fonts are two available options.