nw_to

nw_to is a direction property given to rooms. When a player types, “GO NORTHWEST”, DoGo checks that value to see if there is another room in that direction.

room twistypassage "A Maze of Twisty Passage"
{
    long_desc
        "You are in a maze of twisty passage. There is one exit to the northwest."
    nw_to twistypassage2
}

It is aliased by the inv_desc property.