Defines starting with `d' in bsd/nfs

• DIRHDSIZ bsd/nfs/nfs_vnops.c:368
• DRT_CACHEDROP bsd/nfs/nfsrtt.h:110
• DRT_CACHEREPLY bsd/nfs/nfsrtt.h:109
• DRT_NFSV3 bsd/nfs/nfsrtt.h:111
• DRT_NQNFS bsd/nfs/nfsrtt.h:107
• DRT_TCP bsd/nfs/nfsrtt.h:108