#
  # <public>
  proc useServerId { {serverId ""} } {
    variable downloadUrn
    variable loginUrn
    variable logoutUrn

    verifyServerId $serverId

    if {[string length $serverId] > 0} then {
      #
      # NOTE: Set the URN variables to values that should cause the
      #       specified server Id to be used (assume the server Id
      #       itself is valid and active).
      #

        }
      }
    }

    return ""
  }

  #
  # NOTE: This procedure verifies that the specified value is indeed a valid
  #       server identifier.  The serverId argument is the value to verify.
  #       This procedure may raise script errors.
  #
  # <internal>
  proc verifyServerId { serverId } {
    if {[string length $serverId] > 0 && \
        ![regexp -nocase -- {^[A-Z][0-9A-Z]*$} $serverId]} then {
      error "server Id must be alphanumeric and start with a letter"
    }
  }

  #
  # NOTE: This procedure verifies that the specified value is indeed a valid
  #       version identifier.  The versionId argument is the value to verify.
  #       This procedure may raise script errors.
  #
  # <internal>
  proc verifyVersionId { versionId } {