Some spatial entitites to be perceived and modelled include:

<p>
Location, location class, arbitrary location, 
adjacent location,
location in region, location in volume,
location on path, 
origin, destination, current location,
</p>
<p>
Path, path endpoint, path direction, various useful
path descriptions (e.g., closed-loop path,
linear path, serial path, paralel path)
</p>
<p>
Direction, opposite direction, 
path direction,
</p>
<p>
Distance, closer distance
</p>
<p>
Region, sub-region, region boundary, region capacity,
empty region, populated region, disjunctive region 
</p>
<p>
Volume, sub-volume, volume boundary, volume capacity,
empty volume, populated volume, disjunctive volume
</p>