It is important to understand that MapRun uses your location from GPS to decide that you have reached a control. GPS is not always that accurate, particularly in built-up areas that may not have a clear view of the sky, and the georeferencing of maps on Google Earth (which you will use to locate your controls) is not always perfect. Therefore, MapRun gives you an amount of leeway. By default, the tolerance is 15m, but this can be set when a course is uploaded. In each control location, imagine looking down on a circle with a radius of 15m (diameter of 30m) on the ground around the control. This means the following:

• Cannot place a control on one side of a fence or wall and expect it not to punch from the other
• Specifying a side of a feature is likely to be overkill
• Controls should not be placed in narrow alleyways with high walls on each side
• Controls should not be in a covered area
• Placing a control next to an area which is OOB effectively shrinks the hit area into a semi-circle (or a quarter-circle if an inside corner)

Picking control locations

Runners need to be confident that they are in the correct location when they get to a control as they may need to slow their pace and wait for the punch to occur. If the control does not punch, they should be happy they were in the right place and be able to move on, as they (or an admin) can correct their runs later. This means that controls should be on specific mapped features. Just having a control along a linear feature such as a road or path means they will not know exactly where it is. It should be on a bend, junction or perhaps an adjoining feature such as a hedge end. As the feature should be mapped, this means that using the simplified OpenStreetMap StreetO layout will lead to a simpler set of control descriptions and there is nothing wrong with that.

An exception to the rule about control features being mapped is if you are very clear what the control feature will be and if it is clear and unambiguous when the runner has reached it. This works particularly well if all the controls are on the same type of feature (then you don't need to think about control descriptions at all). Example used successfully by various clubs include:

• Postboxes
• Fire hydrants
• Road junctions (best to stick to same side, e.g. NW)

Control numbers: Line course

For a line course, it does not strictly matter what control numbers you choose. However if runners are running with a watch, the control number punched will show on its display. With a phone, they will either have less information (if it is strapped to the arm where the display cannot be seen) or more information (if the screen is visible, the map and location may be shown). The sequence number (i.e. 1, 2, 3) will not be shown on a watch, so it can be helpful if the control number is easily relatable to the sequence number as an indication that the correct control has been reached (particularly if other controls are nearby). It is easy to renumber controls in Purple Pen, but you can cannot set a number lower than 31. If you have multiple courses (e.g. a short and long variant) that share controls, it will not be possible to make all courses have sequential control numbers.

The alternative is to rename the controls when editing the KML file in Google Earth (see later) and at this point, they can be renamed to any number (e.g. to match the sequence number), but great care must taken if there are multiple courses and they are not 100% finalised as it is easy for mistakes to be made when editing in multiple places.

Control numbers: Score course

Depending on scoring scheme chosen, the control number may be very important for a score course (and, of course, there is no fixed sequence). Please ensure you understand the scoring scheme you have chosen, and if controls have different scores, it is common for higher scoring controls to be further away from the start or more separate from other controls so that there is a strategic decision to be made about whether it is worth getting them.