Status of a file.
A file could be explicitly deleted if the file system
supports such a user command facility. Alternately,
an existing good file would be automatically deleted
if another good file with the same name were copied in.
Note that deleted files continue to occupy prime
Flash real estate.
A file is marked as having an invalid checksum if any
checksum mismatch was detected while writing or reading
the file. Incomplete files (files truncated either
because of lack of free space, or a network download
failure) are also written with a bad checksum and
marked as invalid.