they receive; Those who are unlikely to live, regardless of what care they receive; Those for whom immediate care may make a positive difference in outcome. For many emergency medical services (EMS) systems, a similar model may sometimes still be applied. In the earliest stages of an incident, such as when one or two paramedics exist to 20 or more patients, practicality demands that the above, more "primitive" model will be used. However, once a full response has occurred and many hands are available, paramedics will usually use the model included in their service policy and standing orders. As medical technology has advanced, so have modern approaches to triage, which are increasingly based on scientific models. The categorizations of the victims are frequently the result of triage scores based on specific physiological assessment findings. Some models, such as the START model may be algorithm-based. As triage concepts become more sophisticated, and to improve patient safety and quality of care, several human-in-the-loop decision-support tools have been designed on top of triage systems to standardize and automate the triage process (e.g., eCTAS, NHS 111) in both hospitals and the field. Moreover, the recent development of new machine learning methods offers the possibility to learn optimal triage policies from data and in time could replace or improve upon expert-crafted models. Concepts in triage Simple triage Simple triage is usually used in a scene of an accident or "mass-casualty incident" (MCI), in order to sort patients into those who need critical attention and immediate transport to the hospital and those with less serious injuries. This step can be started before transportation becomes available. Upon completion of the initial assessment by physicians, nurses or paramedical personnel, each patient may be labelled which may identify the patient, display assessment findings, and identify the priority of the patient's need for medical treatment and transport from the emergency scene. At its most primitive, patients may be simply marked with coloured flagging tape or with marker pens. Pre-printed cards for this purpose are known as a triage tags. Tags A triage tag is a prefabricated label placed on each patient that serves to accomplish several objectives: identify the patient. bear record of assessment findings. identify the priority of the patient's need for medical treatment and transport from the emergency scene. track the patients' progress through the triage process. identify additional hazards such as contamination. Triage tags may take a