@@ -34,13 +34,17 @@ In an open source project, the end use of the codebase varies. People may have c
 
 When we talk about Public APIs in Moodle, we are not referring to the `public` keyword in the method definition.
 
-Instead we are considering how that API feature is used. Is that API feature intended to be, or is there a reasonable expectation that it  may be, consumed in some reasonable way including:
+Instead we are considering how that API feature is used. Is that API feature intended to be, or is there a reasonable expectation that it may be, consumed in some reasonable way including:
 
 - being called or accessed externally; or
 - being overridden in a class OOP sense.
 
 :::
 
+Deprecation applies to all Moodle code, including PHP, JavaScript, templates, React components, web services, and so on.
+
+The Deprecation policy also applies when code is _changed_ in a way that may break other code. This includes the impact it may have upon areas such as themes, hook subscribers, callbacks, and child templates.
+
 ## Moodle Core deprecation process {/* #moodle-core-deprecation-process */}
 
 Once it is decided that a function should be deprecated, a multi-step process should be followed.
 
@@ -0,0 +1,21 @@
+---
+title: Deprecation of templates
+tags:
+  - deprecation
+---
+
+The Mustache Templating system does not formally support any deprecation process, therefore the deprecation _process_ is slightly different, while the principle and intent is the same.
+
+For templates and the output component of them, the deprecation policy primarily applies to the context information used to render the template, and passed into child templates.
+
+The deprecation of Templates follows the same general principle as the deprecation of other Moodle code. That is:
+
+- Breaking changes to a template have the same impact as a deprecation and should be considered in the same way
+- Deprecations should only be on the `main` branch, not on stables. Exceptions to this may be made in certain conditions, including:
+  - where a feature is discovered to have been broken irreparably
+  - to address security issues
+- All deprecations should be noted with an [upgrade note](../../upgradenotes.md).
+- Deprecations are split into three stages:
+  1. Initial deprecation
+  2. Final deprecation
+  3. Removal