This means that you can locate a commander or transport, and then grab all droids around it and assign them to the commander or embark them on a transport.
Example
var basePos = startPositions[playerData[me].position];
var baseGroup = newGroup();
groupAddArea(
baseGroup,
Math.max(basePos.x-20, 0),
Math.max(basePos.y-20, 0),
Math.min(basePos.x+20, mapWidth),
math.min(basePos.y+20, mapHeight)
);