This information was provided by Knut Roll-Lund on August 28, 2018 and explains the structure of EDTASM document files.
Basic Structure of a EDTASM File
1. Normal header of many [0x00] then [0x5A] and marker [0xD3] (just 1 where basic has 3)
2. 6 character uppercase filename. If the filename is less than 6 characters, the remainder is padded with spaces [0x20].
3. Assembly Code (Repeat for Each Line):
      A.      5 digit line numbers begin: 0xB0=0 0xB1=1 and so on 5 digits first is like written, most significant first 110 would be 0xB0 0xB0 0xB1 0xB1 0xB0 i.e. ‘00110’
      B.      A space [0x20]
      C.      The text of the line in uppercase with space 0x20 and tab 0x09 as appropriate.
      D.      CRLF [0x0D] to end the line
4. This continues until [0x1A] to end the file.
Typically the last line of the assembly code would be END START where START is the label indicating execution start. ‘/’ in SYSTEM command would execute from there.
The format is pretty much straight ASCII – no tokenizing or anything. The only special characters are line numbers and the end marker.
It is possible that cassette storage is tokenized because saving will pause for each line. Maybe it is just for or’ing line number with 0xB0. Unfortunately CAS format can’t represent those pauses and fortunately load does not need them.
The EDTASM assembly output is so called load format.