Definitions of "Good", "Poor", "Not Found", "Destroyed"
The NGS does not have official definitions for "Good", "Poor", "Not Found", or "Destroyed". However, NGS employees use these guidelines:
GOOD -- Recovered as described on the datasheet; looks healthy and happy.
POOR -- Recovered, but shows some alarming evidence of damage or movement. Often the marks can get run over, or frost heaved, or the ground is just too soft to support it. If the mark is scarred and leaning (i.e. the victim of a tractor-lawnmower), thrust up from the ground like a mushroom and/or surrounded by tractor ruts, it's Poor. If the disk is gone but some evidence (stem) remains, then it could still be useful; that's a Poor too. Please describe the problem you see in the notes section of the report.
NOT FOUND -- I can't find it. Describe how hard you looked or confused you were, e.g., "not found after 10 minute search; unable to recover because all witnesses are destroyed" or "not found; existence doubtful, entire area is now a new shopping mall."
DESTROYED -- The NGS prefers the more optimistic "Not Found" unless you have direct first-hand evidence that the mark is completely obliterated. Getting a mark listed as Destroyed in the NGS database requires submission of evidence (like a photo) and an e-mail.