---
id: change/bcquality/98
type: change
title: "#98 Add P0 event and interface compatibility knowledge"
summary: Guidance added for event and interface compatibility patterns, covering enum unknown value handling, published interface evolution, subscriber contracts for local and internal events, and shipped event attribute immutability.
tier: official
language: en
tags:
  - feature
  - main
system: development
review:
  state: reviewed
  by: opus
  at: "2026-10-08T02:12:50.333Z"
  flags: []
generated:
  at: "2026-10-08T01:26:53.141Z"
  pipeline: 0.2.0
  prompts:
    extract-change: 1
  input_hash: 363f08f47edd1ff2a0919dff383ef154f876c2ef
evidence:
  - kind: code
    url: https://github.com/microsoft/BCQuality/pull/98
    title: "microsoft/BCQuality#98: Add P0 event and interface compatibility knowledge"
    date: "2026-07-14"
    commit: 363f08f47edd1ff2a0919dff383ef154f876c2ef
    t: null
    quote: null
links:
  learn: []
  objects: []
  features: []
  topics: []
  localizations: []
  videos: []
  posts: []
  guidelines: []
  changes: []
number: 98
repo: microsoft/BCQuality
source_id: bcquality-prs
url: https://github.com/microsoft/BCQuality/pull/98
kind: pr
base_branch: main
major: null
merged_at: "2026-07-14T10:52:00Z"
author: JesperSchulz
author_type: User
community_contribution: false
labels: []
change_class: code
change_kind: feature
behavior_change: false
breaking: false
files:
  count: 19
  additions: 331
  deletions: 32
  al: 19
apps: []
objects_touched: []
objects_unjoined:
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  - path: microsoft/knowledge/events/add-new-event-parameters-at-the-end.md
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    status: modified
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  - path: microsoft/skills/review/al-interfaces-review.md
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obsoletions: []
backports: []
fixes_issues: []
work_items: []
systems:
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joined_against:
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  commit: null
---

# #98 Add P0 event and interface compatibility knowledge

> Guidance added for event and interface compatibility patterns, covering enum unknown value handling, published interface evolution, subscriber contracts for local and internal events, and shipped event attribute immutability.

[Pull request](https://github.com/microsoft/BCQuality/pull/98) · merged into `main` on 2026-07-14 by JesperSchulz · 19 files (+331 -32), 19 AL · feature · tier official · reviewed (checked by Opus)

## What changed

- New samples and documentation for handling unknown enum ordinals using UnknownValueImplementation (BC18+)
- Guidelines for extending published interfaces with versioned siblings and BC25+ extends syntax
- Event parameter compatibility rules clarified: local/internal subscribers bind by name and can omit new parameters; public procedures cannot gain required parameters
- Shipped event attribute flags must not be modified to maintain compatibility
- Targeted review skill cues added for events and interfaces topics

## AL objects touched

- `microsoft/knowledge/events/add-new-event-parameters-at-the-end.bad.al`: modified, not in the BC? snapshot
- `microsoft/knowledge/events/add-new-event-parameters-at-the-end.good.al`: modified, not in the BC? snapshot
- `microsoft/knowledge/events/add-new-event-parameters-at-the-end.md`: modified, not in the BC? snapshot
- `microsoft/knowledge/events/do-not-change-shipped-event-attribute-flags.bad.al`: added, not in the BC? snapshot yet
- `microsoft/knowledge/events/do-not-change-shipped-event-attribute-flags.good.al`: added, not in the BC? snapshot yet
- `microsoft/knowledge/events/do-not-change-shipped-event-attribute-flags.md`: added, not in the BC? snapshot yet
- `microsoft/knowledge/events/prefer-this-over-includesender-in-codeunit-events.md`: modified, not in the BC? snapshot
- `microsoft/knowledge/events/treat-local-and-internal-events-as-subscriber-contracts.bad.al`: added, not in the BC? snapshot yet
- `microsoft/knowledge/events/treat-local-and-internal-events-as-subscriber-contracts.good.al`: added, not in the BC? snapshot yet
- `microsoft/knowledge/events/treat-local-and-internal-events-as-subscriber-contracts.md`: added, not in the BC? snapshot yet
- `microsoft/knowledge/interfaces/extend-published-interfaces-dont-edit-them.bad.al`: added, not in the BC? snapshot yet
- `microsoft/knowledge/interfaces/extend-published-interfaces-dont-edit-them.good.al`: added, not in the BC? snapshot yet
- `microsoft/knowledge/interfaces/extend-published-interfaces-dont-edit-them.md`: added, not in the BC? snapshot yet
- `microsoft/knowledge/interfaces/handle-unknown-enum-ordinals-with-unknownvalueimplementation.bad.al`: added, not in the BC? snapshot yet
- `microsoft/knowledge/interfaces/handle-unknown-enum-ordinals-with-unknownvalueimplementation.good.al`: added, not in the BC? snapshot yet
- `microsoft/knowledge/interfaces/handle-unknown-enum-ordinals-with-unknownvalueimplementation.md`: added, not in the BC? snapshot yet
- `microsoft/knowledge/interfaces/set-defaultimplementation-on-enum.md`: modified, not in the BC? snapshot
- `microsoft/skills/review/al-events-review.md`: modified, not in the BC? snapshot
- `microsoft/skills/review/al-interfaces-review.md`: modified, not in the BC? snapshot

## Context

- Systems: development

Source: metadata of a merged pull request in microsoft/BCQuality (bcquality): title, labels, changed paths and counts, with a summary in our words. No source text and no description beyond one short quote (D10, D61).