# eXeLearning > eXeLearning is an open-source (AGPL-3.0) educational content authoring tool. > Educators create interactive learning materials and export them as SCORM 1.2/2004, > HTML5, EPUB3, IMS Content Packages, or eXeLearning's native `.elpx` package. > The new backend runs on Bun + Elysia + Kysely with Yjs for real-time collaboration; > the frontend is vanilla JavaScript; desktop builds use Electron. This file indexes > the documentation most relevant for LLMs and AI agents working with the project > and especially with the `.elpx` file format. The format is documented exhaustively > in `doc/elpx-format/`. For end-to-end project context, also load `AGENTS.md`. ## ELPX file format — start here for AI generation - [ELPX format hub](doc/elpx-format.md): top-level overview, quick-reference table, ZIP layout at a glance, links to every detail subdoc - [AI generation rules](doc/elpx-format/ai-generation.md): the ten non-negotiable rules, recommended four-stage pipeline (plan → JSON → XML → ZIP), pre-flight checklist, prompt-engineering hints. Read this before generating an `.elpx`. ## ELPX format — container and structure - [Container layout](doc/elpx-format/container.md): every file and directory inside an `.elpx` ZIP, mandatory vs optional, where each entry comes from in the export pipeline - [content.xml reference](doc/elpx-format/content-xml.md): full element-by-element ODE 2.0 reference, DOCTYPE, `` root, ``, ``, ``, ``, plus the bundled DTD verbatim and pointer to the XSD - [ID format](doc/elpx-format/ids.md): `[0-9]{14}[A-Z0-9]{6}` ODE identifier format, generation, lifecycle, and cross-hierarchy synchronization rules - [Metadata properties](doc/elpx-format/metadata.md): every `pp_*` key with type, default, internal-key mapping, plus `userPreferences` and `odeResources` - [Pages and blocks](doc/elpx-format/pages-blocks.md): flat-list navigation model, parent-child IDs via ``, ordering, `exe-node:` internal links ## ELPX format — iDevices - [iDevice catalog](doc/elpx-format/idevices/catalog.md): every supported type (43 modern names, plus legacy/FPD aliases) with category, downloadable flag, description - [iDevice content patterns](doc/elpx-format/idevices/patterns.md): the four storage patterns (Standard JSON, URI-encoded JSON, `