PMI defines four principal change-request types. Updates are changes to formally controlled plans/documents to reflect modified or additional content, such as adding functionality. Corrective action realigns project performance with the plan, which fits actions to recover from a schedule delay. Defect repair modifies a nonconforming product/component, e.g., fixing a corrupt login script. Preventive action ensures future performance stays aligned with the plan, such as installing alarms to detect non-conformances early. These mappings follow PMI’s official definitions.

PMI, PMBOK® Guide, 5th ed., §4.3.3.3 “Change Requests,” p.110 — definitions of corrective action, preventive action, defect repair, and updates (“changes to formally controlled…plans, etc.”).

PMI, PMI Lexicon of Project Management Terms, Version 4.0, p.5 (corrective action), p.17 (preventive action).

Project Management Institute

PMI, PMI Lexicon of Project Management Terms, Version 3.2, p.6 (defect repair).

PMI, PMBOK® Guide 6th ed. Errata, §5.2.4 “Project Documents Updates” (formally controlled documents may be changed).