Posted by Rallaz on Jan 20, 2012; 6:47pm
URL: https://forum.librecad.org/Where-I-can-find-LFF-specification-arcs-tp5158044p5161365.html

The units is a inheritance of QCAD. A letter with height 9 in LFF or CXF (non free) is scaled to 1 unit.
If you draw a text like "And" in LC (LibreCAD) with font ISO and text height 1 the letter "A" have 1 unit of height
and the definition is 9 units height:
[0041] A
0.8333,2.5;5.1666,2.5
0,0;3,9;6,0

The difference between romans.lff and romanc.lff is the font height, both based in hershey fonts
romans -> roman simplex
romanc -> roman condensed

If you are interested in open source you may be of interest LC:
You can edit lff fonts directly in LC
File->Open then select filter "LFF Font", all glyphs are treated as block, then save as LFF

https://github.com/LibreCAD/LibreCAD/blob/master/attf2lff/main.cpp is a ttf->lff converter

and a plugin I have write a shp importer (unfinised) using shapelib from http://www.gdal.org/
future plans are writing shp exporter and dgn import-export using GDAL libraries