[4][5] RoboFog allowed users to script in Python, a language Just's brother Guido van Rossum invented two years prior in 1994.
[5] In 1998, FontLab, rival font editor developer to Fontographer (then owned by Macromedia) added Python to version 2.0 of their application, partially due to the popularity of RoboFog.
[4][9] At the request of David Berlow and Petr van Blokland, Frederik Berlaen started work in 2009 on a font editor that used the UFO as a native format.
[4] Because of the network of apps now being used in the "UFO workflow", "the dependency of FontLab as a central drawing environment had created a bottleneck", in their view.
[12] Shortly thereafter, other font editing programs, such as Glyphs,[11][13] FontLab[14] and FontForge[15] started supporting the UFO as an interchange format.
[17] UFOs are organized with XML-based Property List files in the main UFO file system directory, describing font-wide metadata, like font name and weight, as well as interactions between glyphs, like glyph groups and kerning.
[18] GLIF files can describe glyph Bézier curves in cubic or quadratic formats.
[21] This criticism led to the proposal and adoption of the "UFOZ" format, which is a UFO (version 3 and up) compressed into a ZIP archive.
[12] Another criticism of the UFO is that there is no normalized form, as the order of elements in its files and indent standards are left up to the editor.