[Sls-slp] Addition of two NOTES to AOS 732.0-B pre-publication document ** with attachment **

[Kazz, Greg (US 312B)]

Dear SLP WG,

Attached please find the following updates to AOS SDLP (732.0) based upon the SLP WG review of the pre-publication copy.

The changes were made by the SLP WG during the meeting on Tuesday, Sept. 16, 2025 and are provided in the form of NOTES.

The first note already existed but needed to clarify that what used to be a spare field, must be set to ’00’ in the case that the SCID is used in version 4 or previous issues. NOT to leave it up to the user to “ignore” that field.
The second note warns the user that the B_PDU (bit service of AOS) does not have sufficient size to reach the end of data field, if larger size transfer frames are used (this is a consequence of increasing the FHP field for the M_PDU).

See these two changes highlighted in yellow below:


  *
4.1.2.5.4  Spacecraft Identifier (MSB)
                 *
[Text Box: Issue 5]Bits 42-43 of the Transfer Frame Primary Header shall contain the 2 mandatory most significant bits (MSB) of the Spacecraft ID.

NOTE   –    Missions implementing CCSDS 732.0-B (AOS) issue 4 or earlier set this field to ‘00’.



  *   4.1.4.3.3.4. If there are no valid user data in the Bitstream Data Zone (i.e., the B_PDU contains only idle data), the Bitstream Data Pointer shall be set to the value ‘all ones minus one’.

** NOTE – The Bit Stream Service User should be aware that the maximum transfer frame size is limited to 16384 bits due to the limitation of the B_PDU header Bit Stream Data Pointer. **

If there are no objections, I will pass these changes on to the Secretariat so that AOS SDLP (732.0) Issue 5 will be published as soon as possible.

best regards,
Greg
SLP WG Chair

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