When you create a collaborative BPM, you must always have a top-level diagram defined under a model or a package, which represents the subject of the process model and sets the model scope and orientation.
The top-level diagram must contain only:
An atomic transaction between two partners (Business Transaction)
A Binary Collaboration between two partners that involves the invocation of one or a sequence of Business Transactions (Binary Collaboration)
A Collaboration between several partners that involves the invocation of several Binary Collaborations (Multiparty Collaboration)
For more information, see EbXML Business Process Specification Schema (BPSS).
Organization units (see Organization Units ( BPM))
In a collaborative BPM, organization units are always displayed using the icon representation to designate a user of a process that is engaged in a collaboration with a partner. The role association object is used to define the link with the process. The swimlane representation can only be used in diagrams contained in composite processes to ease the definition of invoking or invoked partners for processes implemented by operations (see Example: Using the Execute Operation Implementation Type).
Extended dependencies you used to a link an organization unit to a process in order to express a binary collaboration are automatically replaced with role association objects.
Role associations (see Role Associations (BPM))
All other tools, except for Package, are grayed out in the top-level diagram Palette.