$:/UpgradeLibrary tiddler for the upgrade process.
The upgrade library is formatted as an ordinary plugin tiddler with the plugin type
library. It contains a copy of each of the plugins, themes and language packs available within the TiddlyWiki5 repository.
This command is intended for internal use; it is only relevant to users constructing a custom upgrade procedure.
The title argument defaults to
See the UpgradeMechanism for more details.