Using AI + manual work locally, a basic changelog proposal (to be reworked) is:

Summary of impactful documented changes:

• Many version schemas now enforce stricter validation semantics: mandatory id/ref/version attributes were introduced or tightened in numerous object/ref structures.
• Key/unique/keyref definitions were expanded or renamed across frames and domain modules; reference integrity checks are broader and stricter in v2.0 validation contexts.
• Several constraints were reshaped (including removal of @order from some keys and selective cardinality/type adjustments), which can change pass/fail outcomes for existing XML instances.
• Publication-level schemas add or adjust integrity scopes (for example around Contract and FarePriceFrame) and align naming of site/path navigation key sets.
• Functional evolution is mostly additive, but existing datasets should be revalidated because compatibility now depends more on explicit identifiers and coherent cross-references.

@TuThoThai @skinkie @ue71603 is that a sound basis, or not that much, in your opinion?

Discussed with @TuThoThai:

• @TuThoThai will provide more important functional changes to highlight
• we will add guidance on how to validate locally with either v1.3.1 or v2.0.0 using xmllint or other tools
• we will encourage people to open issues with question label ; ultimately, one of the best guidances is the XSD validation

Some functional changes to add to the changelog:

• addition of DECK PLAN and all related elements
• addition of languages attributes when using MultilingualString to handle translations of names, instead of using AlternativeName
• creation of privateCodes allowing several PrivateCode for the same element (e.g., ticketing, scheduling, etc.)
• changes to BookingArrangement and its use for flexible services, including relation to ServiceJourneyPattern
• addition of a relation between Facilities and Line
• clarification of abstracts elements
• addition and/or correction of values in enumerations (e.g., MedicalFacility, PassengerCommsFacility, SameZone, QuayType, PurchaseMoment, etc.)
• addition of enumerations such as PropulsionTypes, FuelTypes
• deprecation marking for several elements such as Order, PrivateCode, FlexibleLine, BaselineVersionRef, ExternalOperatorRef, PropulsionType, FuelType