Attribute sets are a collection of event layer attributes you can use to create multiple events with a set of additional, organization-specific attributes in a single edit.
Attribute sets are created using event features in an LRS-enabled feature service. All point and line event layers included in the feature service are configurable as attribute sets. Each editable, non-LRS schema field in an event layer can be added to an attribute set. You can create a unique attribute set for characteristic data such as Pavement Type and Speed Limit.
Configure an attribute set
Attribute sets are helpful in adding multiple point events or adding multiple line events in one edit.
You can create an attribute set that can be accessed by an editor using the Add Multiple Point Events tool or Add Multiple Line Events tool . Attributes in an attribute set can be configured with default values.
In ArcGIS Pro, open the map that contains the feature service whose event layers will define an attribute set.
Click the Location Referencing tab, and in the Events group, click the Attribute Sets button .
The Attribute Sets dialog box appears with the line event default attribute set visible.
There are attribute sets for both point events and line events that contain events and their attribute fields. These attribute sets are the default values for the currently signed in user. You can designate a different attribute set as the default attribute set after saving at least one custom attribute set. In the following image, all of the line event layers in the project are included in the All Line Events attribute set.
If a field has a default value, it is shown when the attribute set that includes that field is selected on the Attribute Sets dialog box. Double-click a default value in the Value column to change its value. Values that are updated on the Attribute Sets dialog box can overwrite the default value set in the database.
When one or more layers in an attribute set are not present in the feature service, the warning icon appears next to the name of the attribute set on the Attribute Sets dialog box.
To create an attribute set for a point event layer type, click the Layer Type drop-down arrow and choose Point Event.
Note:
An attribute set can contain either point events or line events; it cannot contain both.
Click the Attribute Set drop-down arrow and choose Create New Attribute Set to create an attribute set based on the selected layer type.
The Create New Attribute Set dialog box appears.
A default name is provided based on the selected layer type.
Optionally, provide a different name for the new attribute set.
For example, type Pavement Type.
Click OK.
The newly created attribute set appears on the Attribute Set dialog box with all of the line event layers in the feature service listed.
Drag any layer of the layer column to the list on the right to define it as part of an attribute set.
Alternatively, right-click an event layer on the left and choose Add Selected to add it to the attribute set.
In the above image, the Pavement Type event and other line event layers are added to the attribute set.
Note:
Some event attributes are required fields. If you attempt to add attributes from an event layer that includes required fields, the required attributes are automatically added to the attribute set.
Right-click an event layer in the attribute set and choose Remove Selected to move it back to the available event layers list on the left.
Alternatively, drag items from the right side of the dialog box to the left to remove them from the attribute set.
When you're finished adding attributes and providing values in the attribute set, click Save.
Saved attribute sets are stored in the location specified in Attribute Set Folder Location on the Location Referencing tab on the Options dialog box. The ArcGIS Pro project folder is the default attribute set folder location.
Tip:
To share a saved attribute set with other users, click Save As and save the attribute set to an RHAS file. Other users can place this file into their attribute set folder location.
To delete an attribute set, remove or delete it from the Attribute Set Folder Location.
Optionally, click the Set as default button to make this attribute set the default for the signed-in user in this feature service.
Click Close to close the Attribute Sets dialog box.
or Add Multiple Line Events tool 
. Attributes in an attribute set can be configured with default values.
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appears next to the name of the attribute set on the Attribute Sets dialog box. 
to close the Attribute Sets dialog box.