4.6.2 Sequential Media

4.6.2.1 Fixed Block

  For fixed block length sequential media, including but not restricted to optical disks (accessed as a sequential set of records), QIC format 1/4-inch cartridge tapes, and local area networks, FITS files shall be written as a bitstream, using the fixed block size of the medium. If the end of the last logical record does not coincide with the end of a physical fixed block, all bits in the remainder of the physical block containing the last logical record shall be set to zero. After an end-of-file mark has been detected in the course of reading a FITS file, subsequent incomplete FITS logical records should be disregarded.

4.6.2.2 Variable Block

  For variable block length sequential media, including but not restricted to 1/2-inch 9-track tapes, DAT 4 mm cartridge tapes, and 8 mm cartridge tapes, FITS files may be written with an integer blocking factor equal to 1-10 logical records per physical block.