Parameter to capture processing start datetime

[pcuq-ads]

Hello,
I am currently working on the project Reference System for ESA.
I would like to know whether it would be possible to introduce an additional parameter to capture the processing:start_datetime.
I understand that processing:datetime corresponds to the end of the processing.
Thank you.

[emmanuelmathot]

Thank you for raising this @pcuq-ads.

A few thoughts on the proposal:

1. A dedicated processing:start_datetime feels like a fairly niche addition. Could you describe a concrete use case for this information, particularly in a search context? Understanding how users would filter or query on processing start time (vs. end time) would help evaluate whether this belongs in the extension.

2. The existing processing:datetime field does not correspond to a strictly defined moment within the processing pipeline. It is primarily used to filter items based on when they were processed (broadly). It is not explicitly the end of processing, so clarifying that distinction would also be valuable in any proposal.

3. If there is a strong use case, we would welcome a PR that includes a clear field description, the rationale, and ideally a reference to how it is used in the ESA Reference System. That will help the community evaluate the proposal concretely.