I think the "levels of danger" re: escape protocols and sharing space (free vs. protected contact) differs from institution to institution. I have worked at two different institutions (both AZA). At one of them, during my stint all animal escapes were announced on the radio using the same code - so you'd call the same code whether a tiger or a tortoise was out (obviously, specifying which species among all the other pertinent information). I'm not sure if this is still the case at that institution or if they've changed that. However, shortly after I left, they instituted a system where there various levels of contact that a human could have with animals, ranging from full protected contact to full free contact. I believe there were five different levels but am not familiar with their system.
At another facility, there were three different radio calls for an animal escape, indicating their "danger" level. Code red for an animal that was likely to kill or cause serious bodily harm, code yellow for an animal that had the potential to cause serious harm (think a Thomson's gazelle with their horns or a giant anteater with their claws), and code blue for an animal that's not going to cause serious harm (a tortoise or a ferret, etc). After my departure, they went down to two categories by lumping in code yellow with code red, which was... a choice, and I'm not really sure why they went that route. All species had individual SOPs that specified whether keepers were allowed to share space with them and in what situations, protocols, etc.