Create and finalize extension

[m-mohr]

Notes from meeting with Bayer:

determination: algorithm run datetime vs. source data datetime (determination_datetime)

Seasons (up to 3 in South, vary heavily)

• Planted, Harvested (plant once, harvest multiple times)

Ownership changed (management ext?)

Valid from/until

=> Admin vs Activity boundaries

Note from Dan: Timestamps extension could possibly be an Activities extension which has a notion of the field’s seasons’ start and end. Maybe starting with an activity such as tilling and ending with harvest.

[m-mohr]

We decided yesterday to have a dedicated meeting for the timestamps extension with at least @ivorbosloper, @cholmes and me.
Other interested parties are welcome to join, please get in touch here if you are interested.

Generally, the valid_from/until timestamps seem most useful and commonly used. If we can't agree on a full timestamps extension we could potentially extract those into a validity related extension and release separately and earlier.