Use identifiers to add unique labels to each of your components.

If you create a Mastery Profile, Module, Topic, Concept, or Activity and leave the identifier field blank, the system will automatically generate an identifier.

Mastery Profile context panel for World Geography Mastery Profile. The identifier field is shown with a value of P-AA18.

The identifier prefix indicates the item level:

PMastery Profile

Identifiers are a great way to track components, especially if you plan on editing the names later on. They are also helpful when creating multi-lingual content as they'll never be translated.  This allows you, and others, to continue tracking the component using the original identifier.

Identifiers are global to the item they identify, and therefore are not available for translation.