diff --git a/README.md b/README.md
index 5378410..d895faa 100644
--- a/README.md
+++ b/README.md
@@ -64,7 +64,7 @@ Junco is an engine and air data front end for aircraft that existing open avioni
 
 | Project | What it does | How Junco relates |
 |---|---|---|
-| [Open Checklists](https://openchecklists.net) | Aircraft profiles and checklists for Part 103 and experimental aircraft | Junco reads aircraft profiles from here. The profile format specification lives in that repository; `spec/aircraft-profile.md` redirects to it |
+| [Open Checklists](https://openchecklists.net) | Aircraft profiles, and a machine-readable checklist library with provenance and verification state, for Part 103 and experimental aircraft | Junco reads aircraft profiles from here, and consumes the checklist, preflight-log and pilot-logbook schemas defined there. Both formats and all of that tooling live in [that repository](https://github.com/allenmcghan/openchecklists); `spec/aircraft-profile.md` redirects to it |
 | [MakerPlane](https://github.com/makerplane) | FIX-Gateway data broker, pyEFIS display, CAN-FIX bus protocol for experimental aircraft | Junco publishes into FIX-Gateway through a plugin, so pyEFIS can display Junco data. CAN-FIX is the bus candidate for v2 |
 | [Stratux](https://github.com/cyoung/stratux) | Dual band ADS-B receiver on a Raspberry Pi | Junco does not receive ADS-B. Traffic comes from a receiver the pilot already owns |
 | [AP_Periph](https://dronecan.github.io/Implementations/AP_Periph/) | ArduPilot's DroneCAN peripheral node firmware | A candidate for the v2 bus stage. Not used in v1: no BLE, STM32 only, and no thermocouple or ignition-pulse tach support |
diff --git a/spec/aircraft-profile.md b/spec/aircraft-profile.md
index ea867b7..896fa48 100644
--- a/spec/aircraft-profile.md
+++ b/spec/aircraft-profile.md
@@ -10,6 +10,21 @@ The aircraft profile format is defined and versioned in the openchecklists
 project, which also hosts profiles for common Part 103 and experimental
 aircraft and the checklists that accompany them.
 
+Two formats live there, and they are deliberately different. **Aircraft
+profiles are TOML**: hand-edited hardware configuration, no upstream document
+to cite. **Checklists are JSON** against a published schema, because a
+checklist carries a source and a verification state that has to survive being
+converted to every other format. Junco consumes both, plus the preflight-log
+and pilot-logbook schemas:
+
+- **Checklist schema:** [schema/open-checklist-1.0.schema.json](https://github.com/allenmcghan/openchecklists/blob/main/schema/open-checklist-1.0.schema.json)
+- **Preflight log:** [schema/open-checklist-log-1.0.schema.json](https://github.com/allenmcghan/openchecklists/blob/main/schema/open-checklist-log-1.0.schema.json)
+- **Pilot logbook:** [schema/open-logbook-1.0.schema.json](https://github.com/allenmcghan/openchecklists/blob/main/schema/open-logbook-1.0.schema.json)
+
+Checklist phase identifiers are stable and semantic, which is the property
+Junco depends on: it is what lets the app map a checklist section to a moment
+in flight rather than to a page number.
+
 Junco firmware and the Android app implement the current schema version of
 that specification. Incompatible schema version changes will be tracked in
 the Junco changelog.