A No Sidewalk label should be placed if there is a missing sidewalk where there should be one.

Where and how should I place a No Sidewalk label?

You should place a No Sidewalk label starting where the sidewalk ends, and then continue placing labels every few feet (about 1 per panorama) until you reach a place where the sidewalk begins again.

You should not place No Sidewalk labels in narrow side streets or alleys.

Do I place a No Sidewalk label on a median?

You should not place No Sidewalk labels on a median that separates the two directions of traffic, unless the median has a sidewalk that abruptly ends.