概念：Release Iteration

A Release Iteration/Sprint (sometimes called a Hardening Iteration/Sprint) is one in which no new features are developed; rather, other activities that add value to the product are performed before its release.

Typical activities that occur during a Release Sprint/Iteration include:

Removing accrued technical debt
Fixing critical and major defects
Finalizing integrations to other systems
Documenting various aspects of the product, including support and user documentation
Significant functional, performance, load, system, user acceptance, and integration testing
Training support personnel and end users
Drafting an Implementation Plan and/or Deployment Plan

Sometimes development teams will split into two - one subteam works on release hardening activities, while the other works in parallel using a separate stream, developing new features for a follow-on release.