Sites

One database can hold several sites. A site is a Relatude.DB collection (ISystemCollection, which the CMS's ISite is). A node is in one site or none, the same for all its revisions. Shared content, such as templates, is in none. Reads are never limited to a site.

A node read says its site in $collection. update-meta with collectionId moves the node to another site, or with null to none.
A site names the languages its content is written in (its Cultures); one that names none takes any. sites lists them, and add-culture with site adds one.
The context's collection is the site the user works in. insert and tree-create put new nodes in it, and a new site goes in itself.

The store does not tie a node's languages to its site: that is the CMS interface's rule for new content. A node moved or copied in the tree keeps its site, so a page can sit in one site's tree but belong to another site, or to none. Two maintenance tasks put such content right. Administrators run them under Maintenance in the CMS interface, or with maintenance-run. Check reports what is wrong, and Fix also repairs it.

Task	Does
`site-collections`, Ensure matching system collection and site	puts every node of a site's tree in that site, and each site in itself
`neutral-culture`, Add a language to neutral content	moves every node of the chosen site whose versions are all neutral into the chosen language, drafts and archived versions too

neutral-culture works on the nodes in the site, so run site-collections first when the site's tree holds nodes from elsewhere. Afterwards a reader of no language, such as a visitor at an address that names none, no longer finds what was moved, so the site has to read in that language or fall back to it. The task warns about this before it fixes.