Primary triage, based on vital signs, is the first and the most important stage of mass casualty situations management. There is still no single approach, both among experts in emergency medical care and among developers of decision support systems. This is explained by the existence of various medical protocols (mandatory for execution at the national level), focusing on the main types of disasters that prevail in the region. In this article we describe the formalization process, aiming to create an efficient inference for casualty prioritizing, based on vital signs.