I have no idea, this is all that is sourced from the American Civil War Research Database:

Sources used by Historical Data Systems, Inc.:
- Mississippi Confederate Grave Registry

You might want to contact:

Historical Data Systems, Inc.
P.O. Box 35
Duxbury, MA 02331
(800) 244-3446
(781) 934-1353
EMail HDS at civilwardata@sprynet.com