Careful and clear documentation of the requirements needed to implement electronic messaging is vital. The requirements define what is needed to the work of the electronic messaging. These requirements can help prioritize the work to be done and can be referenced in the scope of work of a contractor or vendor.The requirements should define the “what” not the “how” of the system updates, and should be actionable by the system developer. The Public Health Informatics Institute (PHII) has published an article on documenting requirements.