Changes
{| class="wikitable"
|-
! Field !! Bytes !! Name !! Notes
|-
| rowspan="10" | System || 0 || User number || 0-15, or #E5 for deleted entries
|-
| 1..8 || Filename || Unused characters are filled with space
| 23 || First block || Set to #FF, only used for output files
|-
| rowspan="3" | User || 24..25 || Logical length || Actual file length is here. As per cassette
|-
| 26..27 || Entry address || The execution address for machine code programs. As per cassette
| 28..63 || Unused || As per cassette
|-
| rowspan="3" | AMSDOS || 64..66 || Real length || Length of the file in bytes, excluding the header record. 24 bit number, least significant byte first. Just a copy, not used!
|-
| 67..68 || Checksum || Unsigned sum of all bytes until this field
| 69..127 || Unused ||
|}
These headers are detected by checksumming the first 67 bytes of the record. If the checksum is as expected then a header is present, if not then there is no header.
