FILE HEADERS

QDOS file headers consist of a 64 byte file data block in the directory.

Filenames can be up to 36 characters long (not including the drive name).

Executable files have file type 1 and an associated dataspace value, while
ordinary data files (including BASIC programs) are file type 0

OFFSET LENGTH    DESCRIPTION
$00    long      file length (in bytes)
 (decimal 0)

$04    byte      file access key (not implemented on original QLs)
 (decimal 4)

$05    byte      file type
 (decimal 5)     0=a data file or SuperBASIC program
                 1=an executable file
                 2=SROFF relocatable object file
                 255=directory
                 3=Thor directory
                 4=font file in 'The Painter'
                 5=pattern file in The Painter
                 6=4 colour mode compressed picture in The Painter
                 11=8 colour mode compressed picture in The Painter

$06    8 bytes   if file type is an executable file (type 1), the first long
 (decimal 6)     word contains the default dataspace size of the program in
                 bytes. The two long words here contain file type-dependent
                 information

$0E    word      length of filename
 (decimal 14)

$10    36 bytes  characters of the filename
 (decimal 16)

$34    long      file update date
 (decimal 52)

$38    long      file reference date
 (decimal 56)

$3C    long      file backup date
 (decimal 60)

SERIAL PORTS

If a file is sent with header over a pure serial link, it is preceded by a byte
value $FF (decimal 255), followed by the first 14 bytes of the file header,
according to the QL Technical Guide (see details of FS.HEADS trap #3, d0=$46
(page 101)