1. The first is the Datum which is the theoretical centre of the earth in broad terms. The Datum used will depend on your position on the earth due to the different radii covering the globe. The globe is not a soccer ball but more in the shape of an egg lying on its side.
2. The second is the Co-ordinate Format. The co-ordinate format is the grid net draped over the globe to give reference to a point whether it be numerical or alpha numerical. The more common format used is geographical co-ordinates (Latitudes and Longitudes) but these co-ordinates alone can be displayed in three formats.

1. Direction measurement (Magnetic North or True North or Grid North).
2. Angular measurement (Degrees, Mils).
3. Presentation format of co-ordinates.

The Geographical Co-ordiante : Degrees Minutes and Seconds (hddd mm ss.s)

This is the format that I was taught back as early as the late 1960’s and the format taught in early times.

1. To my knowledge it is the international standard for aviation,
2. It is the format taught at the accredited training institutions for rescue personnel,
3. It is easy to understand, but difficult to apply due to the continually changing values and  to the  curvature of the earth.
4. Not always easy to apply to all maps as in some countries only every 5 minutes are indicated. One has to first divide into single minutes and only then into seconds (time consuming and less accurate)
5. It is endorsed by the Chief Directorate Surveys and Mapping

The Geographical Co-ordinate : Degrees Minutes and decimals of minutes (hddd mm.mmm)

1. The default in most handheld GPS receivers in South Africa.
2. The format used by most 4x4 users as it is the default in their GPS and due to them not realizing there are other formats.
3. It is easy to understand but difficult to apply due to the continually changing values and to the  curvature of the earth.
4. It is not always easy to apply to all maps as in some countries only every 5 minutes are indicated. One has to first divide into single minutes and only then into decimal of minutes (time consuming and less accurate)

UTM (Universal Transverse Mecator System)

1. The format used by most of our neighbouring states
2. The format used by most 1st world countries
3. Difficult to understand but very easy and simple to apply as it is a metricated co-ordinate system.

1.    Orientation : True North is my selection as the GPS can always orientate to true north but you need to know the magnetic declination in your part of the world. Remember this declination changes constantly and is different in every part of the world, (2 different 1:50 000 Topo maps will have slightly different declinations even if lying next to each other)

2.    Angular measurement : Degrees most common. The other common setting mils is only used by the military and related business and therefore not suited for civilian use.

3.    Presentation format of co-ordinates : I believe this is a crucial setting as this is where human error occurs. (See examples below).

1. I believe any co-ordinate should now include the datum before the actual co-ordinate.
2. The correct co-ordinate symbology must be displayed at all times
3. In Geographical co-ordinates a 0 (Zero) should be added in front of the longitude section of a co-ordinate. By so doing this reserves space for an eastern value exceeding more than 99º E. My reasoning is that a lot of websites are rotating their Latitude and Longitude values. (A South African example would be, Pretoria (Gauteng) that now moves to a position near Harrismith (Free State)
4. If the format degrees minutes and decimal of minutes are used then 3 decimals should be used as no misinterpretation can occur.
5. When using geographical co-ordinates the S should have a tag at the beginning of the S and at the end to prevent people misinterpreting a S for a 5

Examples :

a.    WGS 84  S 27 º 15’ 46.9”  E 029 º 22’ 16.7”
b.    WGS 84  S 27 º 15.438’  E 029 º 25.679’
c.    Cape Zone 35 E 3578261 N 6782319