Font Types

Font Types
.dfont

TrueType

Type 1

Open Type

From http://www.peachpit.com/articles/article.asp?p=31702&seqNum=9&rl=1:

Windows PCs can also use TrueType fonts, but a Windows TrueType font file has a somewhat different format from a Mac TrueType font. Fortunately, Mac OS X recognizes the following Windows versions of TrueType fonts: TrueType fonts (with the extension .ttf) and TrueType collections (with the extension .ttc). Note: Mac OS X believes that any font with a .ttf extension is a Windows TrueType font, so don't use this extension for Mac TrueType fonts.

Conversion Tools
Font Tools -- a set of command line tools from Apple to examine the installed fonts. It's advantage over the GUI Font Book is that it displays the correct names.

Fondu -- A set of programs to interconvert between mac font formats and pfb, ttf, otf and bdf files on unix.

FontForge -- an editor, which can read and write most fonts. It allows you to examine the individual glyphs, and assign them to other unicode character points. While it can read most font files; I did found some problems with fonts some type of ligatures (alternative glyphs for the same character to be exact).

Font Suitcase and .dfont files
A Font Suitcase is a Mac OS 9 font file. A .dfont file is actually the very same format, but only the resource fork of the font file is now moved to the data fork, to make it more compatible with the Mac OS X file system.

The conversion from Font suitcase to .dfont file is rather simple: cat "my OS 9 font"/rsrc > "my OS X font".dfont

The conversion from .dfont file to Font Suitcase is also pretty straightforward: touch "my OS 9 font" cat "my OS X font".dfont > "my OS 9 font"/rsrc SetFile -t "FFIL" -c "DMOV" "my OS 9 font"