> ## Documentation Index
> Fetch the complete documentation index at: https://docs.aseeflow.org/llms.txt
> Use this file to discover all available pages before exploring further.

# CMMN Concepts

This section introduces the concepts behind CMMN. Understanding these concepts is important when designing and implementing Cases with CMMN.

* [**Plan Items and Item Definitions**](/reference/cmmn11/concepts/plan-items) — The building blocks of a case.
* [**Plan Item Lifecycles**](/reference/cmmn11/concepts/lifecycle) — How plan items transition through their states.
* [**Entry and Exit Criteria**](/reference/cmmn11/concepts/entry-exit-criteria) — Sentries that control activation and termination.