I had a discussion about this topic with a co-worker.
We are working implementing a GPS validation system, and I told him the longitude -180 (or 180W) is not a valid longitude because a valid longitude is the same value as one of the angular values of the spherical coordinates, and the latitude is the another one.
In spherical coordinates:
Theta must be (-180,180]. Theta does not contain the -180 as a valid value
Phi must be [-90,90]. Phi contain both values as valid ones
He said to me there must be 2 values of meridian 180 (positive and negative 180 degrees, +180 & -180, or 180E and 180W), and there is no document specifies this issue: [45,-180] is a valid location? Is not the exact position as [45,180] one?
Any online tool I found on the net or code available includes both meridians as different values, but in the real world, are the same!
My question is: Is there any document specifies the 180 meridian can be positive and negative or any document specifies the 180 meridian must be unique? This co-worker does not accept any math demonstrations, therefore any spherical coordinate to rectangular coordinate system will not be a valid reference for this person.