# 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 [appendArgs \ 
          "persistent root directory \"" $persistentRootDirectory \ 
      error "persistent root directory does not exist and could not be created" 
          "\" does not exist and could not be created"] 
    } 
  } 
 
  # 
  # NOTE: This procedure returns the name of the package index file for the