[Proj] ESRI's standard_parallel_1 for Mercator morphed to latitude_of_origin?

[Joseph White]

Mikael,
It's not just you.  In the course of our software, we have to transition
data back and forth from ESRI to GDAL/OGR, and we have to do some
parameter name munging to get ESRI to take some of the coordinate system
data.  

Joe

-----Original Message-----
From: proj-bounces at lists.maptools.org
[mailto:proj-bounces at lists.maptools.org] On Behalf Of Mikael Rittri
Sent: Thursday, October 11, 2012 4:43 PM
To: PROJ.4 and general Projections Discussions
Subject: [Proj] ESRI's standard_parallel_1 for Mercator morphed to
latitude_of_origin?

This question really concerns GDAL/OGR rather than Proj.4, but anyway:

I have had a problem that I think was caused by 

http://trac.osgeo.org/gdal/changeset/7542

which caused the Mercator parameter "standard_parallel_1" in ESRI WKT to
be renamed to "latitude_of_origin" during conversion to OGC WKT. 

This makes no sense to me. These are different parameters with different
semantics, and according to
http://www.remotesensing.org/geotiff/proj_list/mercator_2sp.html
both of them are valid parameter names for Mercator (2SP) in OGC WKT.

So why the renaming? Is the semantics subtly different in the ESRI
world? 
Or is this just a bug that has survived because a Mercator seldom has a
non-zero standard parallel?

I'd be grateful for comments. 

Mikael Rittri
Carmenta
Sweden
http://www.carmenta.com
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