I'm setting the Coordinate System of a data frame that spans the equator. In the past, working in non-equatorial regions but where the data frame horizontally spans two UTM zones, I have selected the UTM zone that most covers the data frame. However, I don't believe my method has been correct.
I have a data frame that mostly displays the N hemisphere, but has a strip at the bottom which is in the S hemisphere. Following the above method, I set the coordinate system to WGS 1984 UTM Zone xxN. However, this has resulted in no latitudinal MGRS labels, except "0" for the equator and "1000mN" for the latitudinal line 1,000m SOUTH of the equator (which incidentally is recessed in towards the data frames' neat-line).
When I change the coordinate system to WGS 1984 UTM Zone xxS, all the labels populate, starting with "9999000mN" at 1,000m S of the equator, "10000" at the equator, followed by "01" at 1,000m N of the equator, "02" at 2,000m N of the equator and so on.
My question therefore is this: Should the coordinate system for a data frame be set based on the location of the lower-left (SW) corner? I appreciate that this may likely just apply to UTM projections.