xDBML Specification
This is the canonical home of the xDBML specification. xDBML follows Semantic Versioning, adapted for a specification: MAJOR.MINOR.PATCH where MAJOR indicates incompatible changes, MINOR indicates backward-compatible additions, and PATCH indicates clarifications. See GOVERNANCE.md §9 for the full stability commitments.
Stable link
xdbml.org/spec/current always serves the newest draft. Bookmark it to follow the specification without editing the link each release. Every version keeps its own permanent URL as well, so a citation or a link in an issue can pin the exact text it refers to.
Available versions
| Version | Status | Released | Notes |
|---|---|---|---|
| v0.6 | Draft -- current | 2026 | Adds constraints: a constraints { } block declares the primary key, unique keys and check expressions of an entity, each with an optional constraint name; keys may be composite and, in document stores, nested (§10). Check expressions are written in single quotes, with backticks as an alias. A referential relationship must reference a key of an entity that declares keys, for relational targets and logical models (§11.17). Every v0.5 document remains valid: in documents declaring earlier versions, a parser reports the new rules on older constructs as warnings. |
| v0.5 | Draft -- superseded | 2026 | Adds supertype groups: a SupertypeGroup declares a supertype and its subtypes along one axis of specialization, with completeness and exclusivity, inherited attributes and identity, and the materialization strategy intended for physical derivation (§12). Chapters from Edge onward move up by one. Strict superset of v0.4. |
| v0.4 | Draft -- superseded | 2026 | Adds the foreign master relationship type: a Ref may carry a foreign_master flag recording where a duplicated attribute of denormalized data is mastered (§11.10), with the derived fk/fm/dk/dm attribute roles (§11.12). Strict superset of v0.3. |
| v0.3 | Draft -- superseded | 2026 | Adds remote module sources: use/reuse may import a module from an https:// URL in addition to a relative path (§26.17). Strict superset of v0.2. |
| v0.2 | Draft -- superseded | 2026 | Adds the module system (use/reuse directives with optional clone blocks), scalar Named Types, and field-level imports. Strict superset of v0.1. |
| v0.1 | Draft -- superseded | 2026 | Initial public draft. Documents declaring xdbml: 0.1 continue to parse correctly with v0.1 semantics under any v0.2+ parser. |
A v1.0 release is planned once the specification has been validated by independent implementations, at least one production deployment, and review by at least one adjacent-standard community. See GOVERNANCE.md §1 for v1.0 release criteria.
Stability commitments
For documents declaring a specific version (e.g., xdbml: 0.2 at the top of the file):
- The behavior of every construct present in that version is preserved across all subsequent MINOR and PATCH versions of the same MAJOR.
- Newer parsers must continue to accept older documents with their original semantics. A
xdbml: 0.1document parses with v0.1 semantics even under a v0.2+ parser. - Documents declaring no version are treated as DBML 3.13.6 by every xDBML parser, preserving full compatibility with the upstream.
Choosing a version
If you are writing new xDBML documents, use the latest draft (currently v0.6). If you are reading documents authored elsewhere, the document's first line declares which version's semantics apply.
If you are an implementation author, support the latest version. Support for older versions is automatic if you implement the version declaration mechanism correctly -- versioned semantics are additive.
Source
Each specification version is maintained as a markdown file in this directory:
v0.6.md-- current draftv0.5.md-- supersededv0.4.md-- supersededv0.3.md-- supersededv0.2.md-- supersededv0.1.md-- superseded
See CHANGELOG.md for what changed between versions.
Substantive changes follow the contribution process. Refinements within a published version (typo fixes, ambiguity clarifications) are handled as patch-level updates.