There is only one file type that uses the .JRTF extension:
JAmes OS Rich Text File
Rich text file used by JAmes OS, an emulated operating system that runs in Windows; may contain bold type, italics, and different fonts as well as simple formatting elements; used for saving text files in JAmes OS.
The JRTF format is the same as an .RTF file, except that it is used by JAmes OS. Therefore, any text editor that opens RTF files can also open JRTF files.
Updated: October 31, 2010