A mnemonic device used in some schools designed to help students when drawing up maps. BOLTS stands for:

B - Border
O - Orientation
L - Legend
T - Title
S - Scale

The basic idea behind 'BOLTS' is that all maps should include a border, some form of orientation (eg. defining which direction North is), a legend (or 'key') containing all used symbols, a title on what the map is of, and a scale. Some teachers actually take it quite seriously, as I learned in year 7, when failure to take the BOLTS rule into consideration resulted in an evil 'UNSATISFACTORY' grade.

Sometimes an extra S is added in to represent 'source'. In other words, if someone used another source or sources to draw up their map they should state so.