.efl is External Format Language File
Key Features: .EFL File Extension
What is an .EFL file?
Formatting file used by NFBTRANS, a Grade Two braille translation program developed by the National Federation of the Blind (NFB); contains instructions that direct the translator how to process a given input file.
EFL files may be global (used by multiple text files) or specific to a single file. Specific EFL files have the same filename as the text file, i.e. "document1.txt" and "document1.efl."