[postgis-users] srid

[Andy Anderson]

On May 25, 2008, at 2:20 PM, Andy Anderson wrote:

>> SRID is an index into the table of datums/projections/coordinate  
>> systems that PostGIS maintains; the commands to create that table  
>> are in the file spatial_ref_sys.sql that comes with the distribution.
>>
>> If you want to build your own transformation, you could start with  
>> one of the listed INSERT statements that matches the type of  
>> projection, and change the coordinates to match your interest. Then  
>> add it to the existing table with an SRID that isn't being used.
>>
>> By the way, the SRID is part of the EPSG standard <http://en.wikipedia.org/wiki/SRID 
>> >, so keep that in mind for future potential conflicts.

I just noticed the specifics for this in the Readme document in <http://www.epsg.org/databases/Discv6_15sql-PosgreSql.html 
 > where it says:

> EPSG Codes
>
> The OGP Geodesy Subcommittee has reserved the integer range 0 to  
> 32767 for use as codes.
> As of dataset version 6.3, the integer range from 60,000,000 to  
> 69,999,999 was also reserved
> for codes for geographic CRSs in explicitly described degree  
> representations, but this is no
> longer supported. To prevent conflict with future additions to the  
> EPSG dataset, users who
> wish to augment the data with their own information should utilise  
> codes greater than 32768
> and outside the 60 million number range indicated.
> If users wish to supplement the change table with their own entries,  
> it is important that the
> user's change notice IDs be above the EPSG integer code limit of  
> 32,767.0. Such an entry in
> the change table is required for users to deprecate any erroneous  
> user data.

-- Andy