Choose the Replace... menu item to return an element
  reservation to the library and create a new generation of
  the element.

  The replace transaction transfers a file from your
  default directory to the current CMS library, thus
  creating a new generation.  The number of the new
  generation is the number of its predecessor with the
  rightmost level number increased by 1. For example, if
  you reserved generation 1A1, CMS would create generation
  1A2 when you replaced it.

  Replace checks for other current reservations and
  concurrent replacements of the element, and whether you
  are replacing another user's reservation.  If any of
  these situations occur, CMS prompts whether you want to
  proceed with the transaction.  If you execute the
  transaction, CMS records it as an unusual occurrence.