@ -- of the file in the mid check-in.  If the file was renamed as part
@ -- of the mid check-in, then pfnid is the previous filename.
@
@ -- There can be multiple entries for (mid,fid) if the mid checkin was
@ -- a merge.  Entries with isaux==0 are from the primary parent.  Merge
@ -- parents have isaux set to true.
@ --
@ -- Field name mnemonics:
@ --    mid = Manifest ID.  (Each check-in is stored as a "Manifest")
@ --    fid = File ID.
@ --    pmid = Parent Manifest ID.
@ --    pid = Parent file ID.
@ --    fnid = File Name ID.
@ --    pfnid = Parent File Name ID.
@ --    fclass = FileCLASS id.
@ --    isaux = pmid IS AUXiliary parent, not primary parent
@ --
@ -- pid==0 if the file is added by checkin mid.
@ -- fid==0 if the file is removed by checkin mid.
@ --
@ CREATE TABLE mlink(
@   mid INTEGER REFERENCES plink(cid),  -- Checkin that contains fid
@   fid INTEGER REFERENCES blob,        -- New file content. 0 if deleted
@   pmid INTEGER REFERENCES plink(cid), -- Checkin that contains pid