JSGF is a language that describes a (spoken) language's grammar. It was written by Sun Microsystems.
#JSGF V1.0; grammar nav_commands; public <direction> = (up|down|left|right); // one of up, down, left or right public <number> = (one|two|three|four|five); public <move> = <number> <direction>; // combines direction and number into command
official docs https://www.w3.org/TR/jsgf (tut) basics of jsgf https://puneetk.com/basics-of-java-speech-grammar-format-jsgf
python pyjsgf designed to interpret/author JSGF python pocketsphinx includes Jsgf class, and FSG converter
sphinxbaseproject includes a commandline utility to convert jsgf to fsg.sphinx_jsgf2fsg -fsg out.fsg < yourfile.jsgf