MLTERTFLib is C++ source code for moving styled text from MLTE (Apple's Carbon API for styled text fields) to RTF (Rich Text Format) and back again. It is free and open source under the zlib/libpng public license.
The attributes handled by MLTERTFLib are: font, size, foreground color, bold, italic, underline, strikethrough, superscript/subscript, and URL link. Due to an Apple bug, there is one caveat about the URL link attribute: If you want a URL link to be preserved when you go from MLTE to RTF, you must apply the attribute in the same way that my RTF to MLTE code does.
MLTERTFLib.zip, version 1.0, 145K.