There are two types of Categories that exist in Layer.

Categories refer to Layer Categories which are found at the top of your sidenav. These are categories you have created in Layer and their respective elements and fields.

Models is the section below Categories. These refer to Revit Categories which are the model categories from your published models. When a model is published, you will see all instances as elements in these Revit categories. You can also add additional Layer fields into your Revit model categories. Elements can also be created in your Revit model categories in Layer but you will notice that any field values related to the Revit model will be blank.

👉 Note: As a rule of thumb, Layer does not create or alter geometries in Revit. Only parameter values can be synced back into Revit from Layer.

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When to use which:

The distinction between Model categories and Layer categories most often comes up when working with rooms in either Room Data Sheets or Condition Assessment projects.

Your Rooms (Revit) category contains a list of all the rooms in your model shown as elements in Layer. To save the trouble of importing a room list and creating elements, some users may want work directly in the Rooms category to create Document View for their Room Data Sheets or use the list for their Room Surveys.

What is important to remember is that the elements shown under the Revit Rooms Model Category is tied to the published model. Any changes in new published models may affect the list. Even accidentally deleting a room may affect your elements. So for surveys, we recommend using a Layer category where you do not need to depend on a Revit model to make changes or generate rooms. After the survey is done, the information can be kept safely in a Layer category to reflect back on while the Revit model may continue to be updated and changed, without affecting your data.

In the case for Room Data Sheets, there is more flexibility offered by keeping your information in a Layer category. One of the few reasons to make Room Data Sheets directly in a Revit Room Category would be if there is a lot of information that needs to be passed from the Revit model parameters to the Room Data Sheets and the design has been mostly finalized. If there are little changes expected to be made in the model, then there will be less versions of new published models to worry about. If you are in the schematic phase of your project, the amount of design changes that will happen should direct you to keep your data independently in a Layer category.