When you submit a recovery report to the NGS, a window opens to ask you whether or not the mark is suitable for satellite observation. In order to answer this question, you must have checked the surroundings of the mark while you were there. A rule of thumb is that, except for perhaps a couple of utility poles or other very narrow objects, the view of the sky above 15 degrees at eye level must be clear of obstructions in all directions. To measure approximately 15 degrees above eye level, with your thumb pointing straight up, hold your fist out at arm's length so that the bottom of your fist is level with your eye. The tip of your thumb is then at about 15 degrees above eye level.
In addition to the 15 degree rule of thumb above, there are two other rules of thumb to consider. A mark within 2 meters of a utility pole is not suitable for satellite observation. A mark within 5 meters of a chain link fence is not suitable for satellite observation.
Most marks are significantly obstructed but if not, the question is based on your individual judgement of how much obstruction there is. If you are in doubt about the correct answer to the question, just click the "don't know" radio button.