Publication of Baseline 55.1
June 5, 2026
Baseline 55.1 has been published and include updates to the market rules, manuals, and supporting documents. These documents are available on the Renewed Market Rules and Manuals Library and Technical Interfaces webpages.
The IESO advises that updates to Market Manual 4.2 – Operation of the Day-Ahead Market (MAN-110), related to revisions to the Day-Ahead Market initialization logic assumptions to better reflect resource status and availability, will be delayed by up to three weeks. These updates are expected to be published in advance of Baseline 56.0. Further information, including timing, will be communicated via Baseline Plan 56.0.
The baseline process is a formal mechanism used to update market manuals and related documents following recently approved market rule amendments or technical system changes.