George, Here is the answer from the NCA concerning Private Pittman I believe the answer says it all.
"Good afternoon Mr. Brooke,
Sara Leach forwarded your email to me for response. The Nationwide Gravesite Locator (NGL) combines information on 1) burials in the NCA-managed national cemeteries and 2) burials for which a headstone or marker was furnished by NCA. The entry for Richard B. Pittman would be the latter; when a request was made for the “In Memory of” (IMOs) marker, it would have generated a record in the system used by NCA’s Memorial Products Service which would have been imported to the NGL. The NGL does not distinguish between burials and IMOs; thus the phrase “BURIED AT” on the NGL is not strictly accurate. It should be read as has a “headstone or marker at”.
Hope that answers your question.