Clean ontologies content (2)

Author: baanders

articles/digital-twins/how-to-manage-model.md

@@ -5,7 +5,7 @@ titleSuffix: Azure Digital Twins
 description: Learn how to manage DTDL models within Azure Digital Twins, including how to create, edit, and delete them.
 author: baanders
 ms.author: baanders # Microsoft employees only
-ms.date: 02/06/2023
+ms.date: 04/05/2023
 ms.topic: how-to
 ms.service: digital-twins
 
@@ -31,7 +31,11 @@ This article describes how to manage the [models](concepts-models.md) in your Az
 
 ## Create models
 
-Models for Azure Digital Twins are written in DTDL, and saved as .json files. There's also a [DTDL extension](https://marketplace.visualstudio.com/items?itemName=vsciot-vscode.vscode-dtdl) available for [Visual Studio Code](https://code.visualstudio.com/), which provides syntax validation and other features to make it easier to write DTDL documents.
+You can create your own models from scratch, or use existing ontologies that are available for your industry.
+
+### Author models
+
+Models for Azure Digital Twins are written in DTDL, and saved as JSON files. There's also a [DTDL extension](https://marketplace.visualstudio.com/items?itemName=vsciot-vscode.vscode-dtdl) available for [Visual Studio Code](https://code.visualstudio.com/), which provides syntax validation and other features to make it easier to write DTDL documents.
 
 Consider an example in which a hospital wants to digitally represent their rooms. Each room contains a smart soap dispenser for monitoring hand-washing, and sensors to monitor traffic through the room.
 
@@ -40,15 +44,23 @@ The first step towards the solution is to create models to represent aspects of
 :::code language="json" source="~/digital-twins-docs-samples/models/PatientRoom.json":::
 
 > [!NOTE]
-> This is a sample body for a .json file in which a model is defined and saved, to be uploaded as part of a client project. The REST API call, on the other hand, takes an array of model definitions like the one above (which is mapped to a `IEnumerable<string>` in the .NET SDK). So to use this model in the REST API directly, surround it with brackets.
+> This is a sample body for a JSON file in which a model is defined and saved, to be uploaded as part of a client project. The REST API call, on the other hand, takes an array of model definitions like the one above (which is mapped to a `IEnumerable<string>` in the .NET SDK). So to use this model in the REST API directly, surround it with brackets.
 
 This model defines a name and a unique ID for the patient room, and properties to represent visitor count and hand-wash status. These counters will be updated from motion sensors and smart soap dispensers, and will be used together to calculate a `handwash percentage` property. The model also defines a relationship `hasDevices`, which will be used to connect any [digital twins](concepts-twins-graph.md) based on this Room model to the actual devices.
 
-Following this method, you can go on to define models for the hospital's wards, zones, or the hospital itself.
-
 > [!NOTE]
 > There are some DTDL features that Azure Digital Twins doesn't currently support, including the `writable` attribute on properties and relationships, and `minMultiplicity` and `maxMultiplicity` for relationships. For more information, see [Service-specific DTDL notes](concepts-models.md#service-specific-dtdl-notes).
 
+Following this method, you can define models for the hospital's wards, zones, or the hospital itself. 
+
+If your goal is to build a comprehensive model set that describes your industry domain, consider whether there's an existing industry ontology that you can use to make model authoring easier. The next section describes industry ontologies in more detail.
+
+### Use existing industry-standard ontologies
+
+An *ontology* is a set of models that comprehensively describe a given domain, like manufacturing, building structures, IoT systems, smart cities, energy grids, web content, and more.
+
+If your solution is for a certain industry that uses any sort of modeling standard, consider starting with a pre-existing set of models designed for your industry instead of designing your models from scratch. Microsoft has partnered with domain experts to create DTDL model ontologies based on industry standards, to help minimize reinvention and encourage consistency and simplicity across industry solutions. You can read more about these ontologies, including how to use them and what ontologies are available now, in [What is an ontology?](concepts-ontologies.md).
+
 ### Validate syntax
 
 [!INCLUDE [Azure Digital Twins: validate models info](../../includes/digital-twins-validate.md)]