diff --git a/docs/index.rst b/docs/index.rst
index 87103ba16..542e46341 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -44,6 +44,7 @@ Rougail
    :caption: What is it all about
 
    concepts
+   vac
 
 .. toctree::
    :titlesonly:
diff --git a/docs/user_data/yaml.rst b/docs/user_data/yaml.rst
index abbea5ef0..d7791537e 100644
--- a/docs/user_data/yaml.rst
+++ b/docs/user_data/yaml.rst
@@ -1,3 +1,64 @@
-Load user datas from a YAML file
-================================
+Charge user data from YAML file
+===============================
+
+.. note::
+
+    | **Path**: yaml
+    | `*disabled*`
+    | **Disabled**: if yaml is not set in "select for user datas" (step.user_data).
+
+
+
+.. list-table::
+
+   * - Variable
+     - Description
+
+   * - **yaml.filename**
+
+       `UNIX filename <https://rougail.readthedocs.io/en/latest/variable.html#variables-types>`__ `multiple` `mandatory` `unique`
+
+       **Command line**: 
+
+       -yf, --yaml.filename
+
+       **Environment variable**: ROUGAILCLI_YAML.FILENAME
+     - File or directory names where user data are stored.
+
+       If a directory is set, all files with "yml" ou "yaml" extension will be load with alphanum order.
+
+       **Validators**: 
+
+       
+
+       - this filename could be a relative path
+
+       - this file must exist
+
+       - 'file type allowed: "directory" and "file"'
+
+   * - **yaml.file_with_secrets**
+
+       `choice <https://rougail.readthedocs.io/en/latest/variable.html#variables-types>`__ `mandatory`
+
+       **Command line**: 
+
+       --yaml.file_with_secrets
+
+       **Environment variable**: ROUGAILCLI_YAML.FILE_WITH_SECRETS
+     - File that may contain secrets.
+
+       By default, all files can contain secrets. It might be useful to define more precisely which files can contain these secrets.
+
+       **Choices**: 
+
+       
+
+       - all **← (default)**
+
+       - first
+
+       - last
+
+       - none
 
diff --git a/docs/vac.rst b/docs/vac.rst
new file mode 100644
index 000000000..554579eee
--- /dev/null
+++ b/docs/vac.rst
@@ -0,0 +1,14 @@
+Variables as Code
+==================
+
+"Variables as Code" is the practice of managing configuration variables the same way you treat source code.
+
+To do this, we need a typed variable definitions with defaults and validation.
+
+Once defined, variables must be able to:
+
+- provide useful information to the operator to make their choices
+- load user values from differents sources
+- validate the context
+- display and archive the final values in a readable format
+- allow other applications to use these variables