generated: '2026-07-27'
method: searched
source: https://www.ieso.ca/sector-participants/change-management/it-release-schedule
docs: https://www.ieso.ca/Sector-Participants/Change-Management/Pending-Changes-Documents
note: >-
  IESO does not publish a developer changelog in the conventional sense. What it publishes instead is
  a forward-dated IT Release Schedule plus a per-baseline Pending Changes package — a change log that
  runs ahead of the change rather than behind it. Every entry below is taken verbatim from those two
  pages on 2026-07-27; nothing has been back-filled or reconstructed.
scheme: baseline release train, R<major>.<minor>
current_baseline: R55.1
next_baseline: R56.0
cadence:
  category_3: >-
    Twice yearly. "Require market participants to make changes to their own technical interfaces."
  category_2: >-
    Four times yearly. "Require market participants to make a change in procedure or to update
    documentation."
stages: [Preliminary Plan, Feedback Period, Target Plan, Final Plan, Sandbox Implementation, Production Build]
feedback_contact: pending.changes@ieso.ca
entries:
- version: R56.1
  category: 2
  production_build: '2026-12-02'
  preliminary_plan: '2026-08-19'
  final_plan: '2026-10-14'
  sandbox: '2026-10-22'
  breaking: false
  highlights: [Procedure or documentation changes only; no participant technical-interface change required.]
- version: R56.0
  category: 3
  production_build: '2026-09-09'
  preliminary_plan: '2026-05-27'
  final_plan: '2026-07-22'
  sandbox: '2026-07-30'
  comments_due: '2026-08-07'
  breaking: true
  breaking_note: Category 3 — requires market participants to change their own technical interfaces.
  highlights:
  - >-
    SPEC467 Retrofit LDC API — "New LDC API in Retrofit based on eDSM contracts for marketing and
    outreach". Replaces SPEC-188.
  - >-
    MM4.1 Dispatch Data Submission — "Resources may now submit reserve loading point values equal to
    zero for synchronized ten-minute operating reserve offers." Affects market data submission through
    the MIM web services.
  - FORM128 CAA Application — IBR models for FACTS devices added.
  - MM1.4 Connection Assessment and Approval — System Impact Assessment / Technical Feasibility Study deposit and invoicing updates.
  - MM1.5 Market Registration — resource terminology consistency; reliable integration study deposit requirements.
  - MM5.5 Settlement Amounts — modified ORCSB definition regarding inaccessible operating reserve.
  - Charge Types and Equations List — Renewable Generation Connection Compensation (CT1463) adjustment.
  - MM7.1 Grid Operating Procedures — new step added to the EOSCA List for Peak Perks activation.
  - MM7.2 Near-Term Assessments — tie-line connection reference updates.
  - MM7.4 Grid Operating Policies — NPCC Directory #1 alignment correction.
  - MM14.2 Reference Level Procedures — sections 10.1 and 10.3 revisions.
- version: R55.1
  category: 2
  production_build: '2026-06-03'
  preliminary_plan: '2026-02-18'
  final_plan: '2026-04-15'
  sandbox: '2026-04-23'
  breaking: false
- version: R55.0
  category: 3
  production_build: '2026-03-04'
  preliminary_plan: '2025-11-19'
  final_plan: '2026-01-14'
  sandbox: '2026-01-22'
  breaking: true
  breaking_note: Category 3 — participant technical-interface changes required.
- version: R54.1
  category: 2
  production_build: '2025-12-03'
  preliminary_plan: '2025-08-20'
  final_plan: '2025-10-15'
  sandbox: '2025-10-23'
  breaking: false
specification_revisions:
- document: IMO_SPEC_0100 Outbound Automated Document API
  issue: 9.0
  date: '2025-03-05'
  change: >-
    "Updated to reflect various changes to the URL for IESO Reports Site (public reports and REST API
    endpoint)."
- document: IMO_SPEC_0100 Outbound Automated Document API
  issue: 7.0
  date: '2016-02-08'
  change: Updated to document the IESO Report Site URL changes.
- document: SPEC-232 Retrofit Service Provider API
  date: '2024-12-04'
  change: Specification updated.