diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -2,6 +2,13 @@
 
 This is the WIP rewrite of the ESE website.
 
+## Editing the content
+All content is in the `content` directory, in the form of markdown files. There usually no need to install/build the project in order to make changes there.
+
+Additionally, there are some data files in `content/_data`:
+- `ese.yaml`: the year and color is configured here
+- `program.yaml`: see [it's documentation](content/_data/program.md)
+
 ## Building
 
 To build the website, install the dependencies and run the build script:
diff --git a/content/_data/program.md b/content/_data/program.md
new file mode 100644
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@@ -0,0 +1,19 @@
+# program.yaml
+
+The top level keys must be a *quoted date in yyyy-mm-dd format*.
+
+Each contains a list of events, which have the following properties:
+- `start`: time in hh:mm
+- `end`: time or null/omit if open ended
+- `title`, `description`, `location`, `annotation`: either de/en versions (like this [^1]) or simply a string if it should be the same for all languages.
+  - `description`, `location` and `annotation` can use some markdown, e.g. hyperlinks or bold text
+  - `location` and `annotation` can be omitted.
+- `checkin_link`: optionally, a url where people need to register or can find more important information
+- `livestream`: true, if this event will be live streamed. Can be omitted otherwise.
+    
+[^1]: ```yaml
+        title:
+          de: Begrüßung
+          en: Grand Opening
+      ```
+      Both en and de versions must be set and non-empty.