Changes
| 18 || File type || 0:BASIC 1:Protected 2:Binary (ASCII files don't have headers but a fake header is built in memory with the file type #16, "Unprotected ASCII v1")
|-
| 19..20 || Data length || The number of data bytes in the data record. As per cassette
|-
| 21..22 || Data location || Where the data was written from originally. As per cassette
|-
| 23 || First block || Set to #FF, only used for output files
|-
| 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
|-
| 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!
