The ref man scope page (#1289)

* Move scope concept to ref man

* Improve Scenario ref man

* Scope ref man

* Scope ref man

taipy/config/common/scope.py

@@ -35,13 +35,59 @@ def __lt__(self, other):
 
 
 class Scope(_OrderedEnum):
-    """Scope of a `DataNode^`.
+    """Scope of a `DataNodeConfig^` or a `DataNode^`.
 
     This enumeration can have the following values:
 
     - `GLOBAL`
     - `CYCLE`
-    - `SCENARIO`
+    - `SCENARIO` (Default value)
+
+    Each data node config has a scope. It is an attribute propagated to the `DataNode^` when instantiated from
+    a `DataNodeConfig^`. The scope is used to determine the _visibility_ of the data node, and which scenarios can
+    access it.
+
+    In other words :
+
+    - There can be only one data node instantiated from a `DataNodeConfig^` with a `GLOBAL` scope. All the
+        scenarios share the unique data node. When a new scenario is created, the data node is also created if
+        and only if it does not exist yet.
+    - Only one data node instantiated from a `DataNodeConfig^` with a `CYCLE` scope is created for each cycle.
+        All the scenarios of the same cycle share the same data node. When a new scenario is created within a
+        cycle, Taipy instantiates a new data node if and only if there is no data node for the cycle yet.
+    - A data node that has the scope set to `SCENARIO` belongs to a unique scenario and cannot be used by others
+        When creating a new scenario, data nodes with a `SCENARIO` scope are systematically created along with
+        the new scenario.
+
+    !!! example
+
+        Let's consider a simple example where a company wants to predict its sales for the next month. The company
+        has a trained model that predicts the sales based on the current month and the historical sales. Based on
+        the sales forecasts the company wants to plan its production orders. The company wants to simulate two
+        scenarios every month: one with low capacity and one with high capacity.
+
+        We can create the `DataNodeConfig^`s with the following scopes:
+
+        - One data node for the historical sales with a `GLOBAL` scope.
+        - Three data nodes with a `CYCLE` scope, for the trained model, the current month, and the sales predictions.
+        - Two data nodes with a `SCENARIO` scope, for the capacity and the production orders.
+
+        The code snippet below shows how to configure the data nodes with the different scopes:
+
+        ```python
+        from taipy import Config, Scope
+
+        hist_cfg = Config.configure_csv_data_node("sales_history", scope=Scope.GLOBAL)
+        model_cfg = Config.configure_data_node("trained_model", scope=Scope.CYCLE)
+        month_cfg = Config.configure_data_node("current_month", scope=Scope.CYCLE)
+        predictions_cfg = Config.configure_data_node("sales_predictions", scope=Scope.CYCLE)
+        capacity_cfg = Config.configure_data_node("capacity", scope=Scope.SCENARIO)
+        orders_cfg = Config.configure_sql_data_node("production_orders",
+                                                    scope=Scope.SCENARIO,
+                                                    db_name="taipy",
+                                                    db_engine="sqlite",
+                                                    table_name="sales")
+        ```
     """
 
     GLOBAL = 3

taipy/core/data/data_node.py

@@ -57,7 +57,7 @@ def _recompute_is_ready_for_reading(dn: "DataNode", *args, **kwargs):
 class DataNode(_Entity, _Labeled):
     """Reference to a dataset.
 
-    A Data Node is an abstract class that holds metadata related to the dataset it refers to.
+    A Data Node is an abstract class that holds metadata related to the data it refers to.
     In particular, a data node holds the name, the scope, the owner identifier, the last
     edit date, and some additional properties of the data.<br/>
     A Data Node also contains information and methods needed to access the dataset. This