#
    # NOTE: Either the persistent root directory must already exist -OR- we
    #       must be able to create it.
    #
    if {![file isdirectory $persistentRootDirectory] && \
        [catch {file mkdir $persistentRootDirectory}]} then {
      error "persistent root directory does not exist and could not be created"
    }
  }

  #
  # NOTE: This procedure returns the name of the package index file for the
  #       language specified by the language argument.  An empty string will
  #       be returned if the language is unsupported or unrecognized.