ERF files are generated by the Epson R-D1 and R-D1s digital rangefinder cameras.
EPSON is no longer in that business so no other camera use that format.
Epson ERF files are TIFF/EP files. CFA data is in the primary subIFD from IFD0. Thumbnail is 8RGB in IFD0. Exif is attached to the ExifIFD of IFD0.
The CFA image data is “compressed”, bit packed. The Compression value in the CFA subIFD is set to 32769.