feat: adds high level definitions for templates and templates parameters

Signed-off-by: Vincent Biret <vincentbiret@hotmail.com>

Author: baywet

versions/1.2.0-dev.md

@@ -155,6 +155,31 @@ The properties of the `update` or `copy` object MUST be compatible with the targ
   - An object value of the `update` or `copy` property is recursively merged with an object value of the target property.
   - Other property value combinations are incompatible and result in an error.
 
+This object MAY be extended with [Specification Extensions](#specification-extensions).
+
+#### Action template object
+
+This object represents one or more changes to be applied to the target document at the locations defined by the target JSONPath expression and reused in one of more action references.
+
+##### Fixed fields
+
+| Field Name | Type | Description |
+| ---- | :----: | ---- |
+| <a name="action-template-parameters"></a>parameters | [[Action template parameter object](#action-template-parameter-object)] | A list of parameters to be used during  string literal replacement. Optional. |
+| Any field defined in the [action object](#action-object) | mixed | The [string literal replacement syntax](#string-literal-replacement-syntax) MAY be used for any of the fields, and the replacements MUST be evaluated as the template reference is being resolved. |
+
+This object MAY be extended with [Specification Extensions](#specification-extensions).
+
+#### Action template parameter object
+
+##### Fixed fields
+
+| Field Name | Type | Description |
+| ---- | :----: | ---- |
+| <a name="action-template-parameter-name"></a>name | `string` | The name of the parameter, MUST match the key for the string literal replacement expression. Required. |
+| <a name="action-template-parameter-default>default | Any | A default value for the parameter to use when no value is provided by the reference. Optional. |
+
+
 This object MAY be extended with [Specification Extensions](#specification-extensions).
 
 ### String literal replacement syntax