Wikidocumentaries tries to avoid creating local properties. When there is reason to store data, but Wikidata cannot provide a property for that or it is out of scope for Wikidata, a local property can be created. This applies specifically to site-specific application data.

Image
When the user interacts with an image, minimal image metadata gets saved to the local Wikibase. The image can also be immediately saved to Wikimedia Commons. The alternative is that the image gets imported to Wikimedia Commons only when the metadata is mature enough against a schema.

• Original URL
• Commons location
• Blacklisted topics
• Whitelisted topics
• Custom statements
• Similar image URIs
• Wikidocumentaries collections
• Image hash

See evolving work at https://wikidocumentaries.wmflabs.org/wiki/Media_metadata

Article

• Editable / editable only by the creator
• Language
• Link to local wiki (Openly editable could be presented in the same way as Wikipedia articles in Wikidata
• Creator (linking to the user, how?)
• Creation date
• Some kind of privacy/spam assessment?

User
User data should not be exposed to public

• Collections
• Organisations and roles
• Communities

Organisation (user)

• Representatives (users)
• Domains covered (using Schemas)
• Discussions (not necessarily related to Wikibase)
• Wikidata item

Community

• Domains covered (Using Schemas)
• Discussions (not necessarily related to Wikibase)

Collection

• Owner (user)
• Images
• Other content later

Sources (later)

• Original URI
• Wikidata item of the source
• Related Wikidocumentaries topics (maybe whitelisted and blacklisted as with images)
• Specification for precise location
• Quotes