FITS file extension is for Flexible Image Transport System Graphics and data
Similar to FITS
#ST - LocoScript Standard mode printer definition file
$$P - OS/2 Notes file
$$S - OS/2 Spreadsheet
$00 - DOS Pipe file
$1 - ZX Spectrum file in HOBETA format
$D$ - Data
OS/2 Planner
$DB - Temporary file
dBASE IV
View all in File Extensions