Final answer:
Examiners use military regulations and medical literature as references for guidance on service members' ability to perform duties due to health issues, reflecting historical changes in understanding physical and mental health within military service.
Step-by-step explanation:
Examiners looking for guidance on service members' inability to perform duties due to physical defects or medical conditions typically refer to two main sources. First, military regulations and manuals which provide protocols for assessing fitness for service, and second, medical literature that defines various conditions and outlines treatment and prognosis. These references allow for both a consistent approach to assessing serviceability within the armed forces and compliance with relevant laws and guidelines.
During historical periods such as World War II, the criteria for service members' health and ability to serve were often informed by prevailing societal attitudes. For instance, homosexual acts could lead to a discharge, and psychological issues were not deeply understood or sympathized with. Over time, the standards for military service have evolved, becoming more informed by psychological and medical understandings, reflecting a more nuanced approach to physical and mental health in the military.