Transition to OIR 26.1: MasterFormat, OmniClass, UniFormat

Review all three standards with Changes in OIR 26.1

Paid subscribers can open Changes in OIR 26.1 in CSI Dynamic Standards℠ and select MasterFormat, OmniClass, or UniFormat. The tool presents current classifications within their hierarchy, with predecessor information to help users understand how existing references relate to OIR 26.1. It supports reviewing standards information when updating a library, dataset, or project reference; its scope extends beyond MasterFormat documents.

Expand the relevant branches and inspect the displayed change information. The interface identifies changes such as a title change, a number change, or a new classification. Read the predecessor and current reference together before deciding how the change applies to your information. Keep the selected standard and comparison context with your review notes so another team member can retrace the relationship.

Check which predecessor is being compared

For MasterFormat, the tool displays OIR 26.1 classifications with their predecessors in MasterFormat 2020. It explicitly notes that there are no classification transitions between MasterFormat 2026 and OIR 26.1. This comparison should not be described as a list of classification changes from the 2026 Edition baseline to OIR 26.1.

When switching to OmniClass or UniFormat, check the comparison context shown for that standard. Record the standard, edition, and OIR separately on both sides of a transition where available. OIR 26.1 identifies the operational information release; it does not rename an approved standard edition. The release notes explain the wider digital information improvements and standards-development context.

Use the separate MasterFormat Document Transition Tool

For a document workflow, the September 22 changelog states that the Document Transition Tool now supports transitions from any MasterFormat OIR to 26.1. Select the source OIR that matches the document being reviewed and inspect the resulting references against the intended work.

This MasterFormat document capability is separate from the three-standard Changes in OIR 26.1 tool. Use the changes view to understand predecessor relationships across MasterFormat, OmniClass, and UniFormat; use the Document Transition Tool for its supported MasterFormat document workflow. Existing subscribers can log in to access the available tools.

Apply reviewed transitions to your information

Begin with an original copy of the document or dataset and identify the references that need updating. A classification may appear in specifications, estimates, product records, BIM properties, or office libraries. Review the displayed predecessor relationship and current classification before changing each dependent reference. A new number or title does not by itself change a project's technical requirements or contractual scope.

For relationships between different standards, consult the crosswalk guide. A crosswalk and a predecessor transition answer different questions: one connects classification perspectives, while the other helps trace a reference to its current context. Record the source, target, reason for the update, and reviewer. Check a representative sample before applying the same approach to a wider library, and retain historical records in their original context where appropriate.

Release date, standards authority, and access

CIN published OIR 26.1 on September 22, 2026 for information delivered through CSI Dynamic Standards. An Operational Information Release updates the digital information environment. CSI continues to govern, develop, and approve the underlying standard editions through its established consensus process. An OIR number should therefore be recorded separately from the standard name and edition when documenting a project reference.

Use the full release notes for the published scope and the September 22 changelog for the platform changes. The announcement from Chris Anderson explains the release's purpose. These public guides provide orientation; verify individual classifications and relationships in the licensed environment before applying them to project documents. Existing customers can log in, and teams evaluating access can review CSI Dynamic Standards pricing.