Function relate_documents 

pub fn relate_documents(
    tx: &mut Transaction,
    model: &Model,
    relating: EntityId,
    related: &[EntityId],
    relationship_type: Option<&str>,
) -> ClassificationResult<EntityId>

Stage an IfcDocumentInformationRelationship in the layout of model’s declared release.

This is how a document says it supersedes, amends or accompanies another. RelationshipType is a free label rather than an enum: the schema does not fix the vocabulary, so it is written as given. IFC2X3 declares only the three relationship attributes; IFC4 and IFC4X3 add the inherited Name and Description, left unset here.

Errors

Refuses a reference that is not an IfcDocumentInformation, an empty related set (SET [1:?]), a document related to itself, and a header binding no single known release. Nothing is staged on an error.