|@is_a@|string|Arvados object type|@["head_uuid","is_a","arvados#collection"]@|
|@exists@|string|Test if a subproperty is present.|@["properties","exists","my_subproperty"]@|
-h4. Filtering on subproperties
+h4(#subpropertyfilters). Filtering on subproperties
Some record type have an additional @properties@ attribute that allows recording and filtering on additional key-value pairs. To filter on a subproperty, the value in the @attribute@ position has the form @properties.user_property@. You may also use JSON-LD / RDF style URIs for property keys by enclosing them in @<...>@ for example @properties.<http://example.com/user_property>@. Alternately you may also provide a JSON-LD "@context" field, however at this time JSON-LD contexts are not interpreted by Arvados.