rdblue commented on code in PR #15834: URL: https://github.com/apache/iceberg/pull/15834#discussion_r3163317713
########## format/spec.md: ########## @@ -242,10 +242,13 @@ For `geometry` type, the CRS does not affect geometric calculations, which are a The default CRS value `OGC:CRS84` means that the objects must be stored in longitude, latitude based on the WGS84 datum. -Custom CRS values can be specified by a string of the format `type:identifier`, where `type` is one of the following values: +Non-default CRS values are specified by any string that uniquely identifies a coordinate reference system associated with this type. +To maximize interoperability, suggested formats for CRS include, but are not limited to: +* `<authority>:<code>` - where `<authority>` represents some well known authorities, and `code` is the code used by the authority to identify the CRS. Examples are - `OGC:CRS84`, `OGC:CRS83`, `OGC:CRS27`, `EPSG:4326`, `EPSG:3857`, `IGNF:ATI`. See [https://spatialreference.org/](https://spatialreference.org/) for definitions of coordinate reference systems provided by some well known authorities. +* `srid:<identifier>` - A reference using a [Spatial reference identifier (SRID)](https://en.wikipedia.org/wiki/Spatial_reference_system#Identifier), where <identifier> is the numeric SRID value. For example: `SRID:0`. Review Comment: I'd roll this into the last bullet so that we don't have a special case for one we don't think will be used. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
