This DEX is used to communicate information about Requirements after the actual procurement and contracting phase. Later, when the solution is available, the Requirement DEX is used to communicate how the requirements are fulfilled mainly for verification and validation purposes.

The Message Requirement Specification is delivered to the contracted supplier and marks the start of the project; the Requirements are made available on digital form, making it possible for the supplier to start defining the solution tracing the design to the original requirements (and eventually to claim compliance with by sending back Message Requirement Fulfilment (TBD)).

The business processes for which the DEX provides messages for are summarized in the SysML activity diagram in Figure 1.