1.3.2 Project References
Records within Reference Information (section 184.108.40.206.2) in the dir Stream (section 220.127.116.11) define references (1) to external resources that are used by the VBA project. Each REFERENCE (section 18.104.22.168.2.1) in Reference Information (section 22.214.171.124.2) corresponds to a reference (1) to an external resource that can interact via OLE Automation as described in [MS-OAUT].
The three types of external references are as follows:
A REFERENCEPROJECT (section 126.96.36.199.2.6) specifies a reference (1) to external VBA projects that are used by the VBA project.