Tier Certification of Design Documents (TCDD) is an Uptime Institute review that verifies a data center's design drawings meet the redundancy and capability requirements of the targeted Tier before construction. It confirms the intended availability level on paper, but does not by itself certify what is actually built, which requires the separate constructed-facility certification.
Category: Resilience & Availability · Subcategory: Tier & Class Systems · Part of the AIDC Technical Terminology reference.