[Proj] Standard meridians

[Gerald I. Evenden]

While I am in the mood to study changes/enhancements I remember the old 
request for specifying standard meridians.

I previously pooh-poohed the idea as I felt is was a function of the 
application program and not a library operation.

What is a question in my mind is what does the standard meridian correction 
apply to?  All longitude including option control longitude like lon_0, or 
just selected elements that refer to some longitude parameter (lon_0 is the 
only one I can think of).  Does the correction apply to input/output 
geographic data?  If it is both I/O data and control data why 
bother---consider the entire run as in the alternate standard meridian space.

Bottom line: if there is a correction for standard meridian, to what aspects 
of longitude in the projection process does it apply?

-- 
The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939) British psychologist