Posted by Rallaz on Apr 10, 2013; 7:41am
URL: https://forum.librecad.org/Here-a-standard-lff-doubled-tp5707888p5707893.html

lff format was created because the original cxf is proprietary licensed and can't be published.

You can read the file header with a text editor to verify license and more.

Iso.lff & standard.lff (are the same) is based on http://commons.wikimedia.org/wiki/File:ISO3098.svg
and licensed as GPL v2 or later, then, no problem to publish modifications.
I send a patch to current code adding these chars.

About 1.lff be sure you can publish it without problems for the community.

About NABLA, ≤ U+2264 and ≥ U+2265 are unicode names & codes, more info in:
http://www.unicode.org/Public/6.1.0/charts/CodeCharts.pdf (warning: 89Mb)
or a bit more easy to use:
charmap.exe in windows or
kcharselect in windows and linux (kde)