Sharing

 The 'sharing' is a value that specifies whether  other  programs
 can  access  the  file  while  it  is open.  A value of READONLY
 indicates that other programs can read  but  not  write  to  the
 file.   This  is  the  default  value  for files with HISTORY :=
 READONLY.  READWRITE indicates that other programs can read  and
 write  to  the file when it is open.  A value of NONE denies any
 access to the file while it is open.  This is the default  value
 for all other histories.