* ''User'' is an extension of Google User with a //username//
* ''User'' owns ''Namespaces''
* ''User'' owns ''Tiddlywikis''
* ''Namespace'' owns ''Tiddlers''
* ''~TiddlyWiki'', in a ''Namespace'', references ''Tiddlers''
Some rules :
* only the owner of an entity (''~TiddlyWiki'', ''Namespace'', ''Tiddler'') can edit it
* a ''Namespace'' (or a ''~TiddlyWiki'') can be //private//.
* only the owner of a private ''Namespace'' (or a ''Tiddlywiki'') can see it