File sharing restriction

[Sankar Das]

Hi

  Please excuse me if this question is already discussed in this list.

  Is it possible to restrict a file to be acessed by more than one
  user simultaneously? I want to know that if it is possible that
  whenever a user does 'checkout' of some file, nobody will be
  allowed to 'ckeckout' that file until the first user make a 'commit'.

Thanks
Sankar