After you've explored an area to a certain amount you will be able to see obvious exits in the showexits list
[size=150:3a0fwmb1][u:3a0fwmb1][b:3a0fwmb1]Before Exploration[/b:3a0fwmb1][/u:3a0fwmb1][/size:3a0fwmb1]
Wooden Platform
You stand on a narrow wooden deck around the entrance to a stone house
that is apparently the lowest extension of a large stone structure embeded
in the underside of the floating island of Valkyre. A plaque is embedded
in the stone by the arched door into the house. A swaying suspension
bridge leads off to the east.
Exits: East
[size=150:3a0fwmb1][u:3a0fwmb1][b:3a0fwmb1]After Exploration[/b:3a0fwmb1][/u:3a0fwmb1][/size:3a0fwmb1]
Wooden Platform
You stand on a narrow wooden deck around the entrance to a stone house
that is apparently the lowest extension of a large stone structure embeded
in the underside of the floating island of Valkyre. A plaque is embedded
in the stone by the arched door into the house. A swaying suspension
bridge leads off to the east.
Exits: [North] East
The closed exit in this room shows up as [North] of course hidden and invisible exits will remain hidden, and you will need to use powerful magics to see those.