FontLab deals with three main categories of files:
- Source (working) file formats: VFC, VFJ.
- Final font formats: TTF, OTF, PFB, WOFF, EOT.
- Interchange file formats: UFO, XFO, VFB, FOG.
FontLab uses two file formats for saving: VFC (binary) and VFJ (JSON based). Both can contain all elements used in the font design process. Advanced users may want to save their intermediate work in other proprietary formats like UFO, XFO, VFB. You can find the corresponding options in Preferences > Save Fonts. It is also possible to read from proprietary formats like UFO, GLYPHS, FOG, VFB, but this is actually an import operation.
Saving in formats other than VFC or VFJ is actually an export and may lose some elements like glyph notes, pins, element references, etc.
When you export to final font formats you also lose some elements. Things like guidelines, anchors, pins, notes, etcetera will be dropped during export if the exported font format doesn’t support them.
See Font Formats, Other File Formats for more info on file formats.