From e72f7f832cfd63128cb1167ace271ecb5dda83de Mon Sep 17 00:00:00 2001 From: Matthias Mohr Date: Wed, 8 May 2024 13:21:09 +0200 Subject: [PATCH] Add timeliness example and warning --- README.md | 26 +++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-) diff --git a/README.md b/README.md index fc923db..a8a4a7d 100644 --- a/README.md +++ b/README.md @@ -31,9 +31,9 @@ The fields in the table below can be used in these parts of STAC documents: - [x] Assets (for both Collections and Items, incl. Item Asset Definitions in Collections) - [ ] Links -| Field Name | Type | Description | -| --------------------------- | ------ | ----------------- | -| product:type | string | The product type. | +| Field Name | Type | Description | +| --------------------------- | ------ | ------------------------------------------------------------ | +| product:type | string | The product type. | | product:timeliness | string | The average expected timeliness of the product as an [ISO 8601 Duration](https://en.wikipedia.org/wiki/ISO_8601#Durations). | | product:timeliness_category | string | A proprietary category identifier for the timeliness of the product. | @@ -49,6 +49,26 @@ Some extensions may specify more specific rules for this field. This field superceedes the `sar:product_type` field. +#### Timeliness + +Below you can find an example that shows how the timeliness fields could be used. + +The Copernicus programme releases products on three levels of timeliness: + +| Name | Description | `product:timeliness` | `product:timeliness_category` | +| ------------------- | ------------------------------------------------------------ | ----------------------- | ----------------------------- | +| Near Real-Time | Delivered less than 3 hours after data acquisition. | e.g. `PT3H` (3 hours) | `NRT` | +| Short Time-Critical | Delivered within 36 (Sentinel-6) to 48 (Sentinel-3) hours after data acquisition. | e.g. `PT36H` (36 hours) | `STC` | +| Non Time-Critical | Delivered typically within 1 month after data acquisition. | e.g `P1M` (1 month) | `NTC` | + +> \[!WARNING] +> +> Be careful when specifying the durations for `product:timeliness`. It is recommended to closely reflect the semantics of timeliness as specified by the provider. For example, if the timeliness is 36 hours, specify `PT36H` instead of `P1DT12H`, although allowed: +> +> > The standard does not prohibit date and time values in a duration representation from exceeding their "carry over points". Thus, `PT36H` could be used as well as `P1DT12H` for representing the same duration. But keep in mind that `PT36H` is not the same as `P1DT12H` when switching from or to Daylight saving time. +> +> Source: + ## Contributing All contributions are subject to the