Format of sharing record:
Offset  Size    Description
 00h    BYTE    flag
                00h free block
                01h allocated block
                FFh end marker
 01h    WORD    size of block
 03h    BYTE    checksum of pathname (including NUL)
                if sum of ASCII values is N, checksum is (N/256 + N%256)
 04h    WORD    offset in SHARE's DS of lock record (see below)
 06h    DWORD   pointer to start of system file table chain for file
 0Ah    WORD    unique sequence number
 0Ch    var     ASCIZ full pathname

Format of SHARE.EXE lock record:
Offset  Size    Description
 00h    WORD    offset in SHARE's DS of next lock table in list
 02h    DWORD   offset in file of start of locked region
 06h    DWORD   offset in file of end of locked region
 0Ah    DWORD   pointer to System File Table entry for this file
 0Eh    WORD    PSP segment of lock's owner