Available with Location Referencing license.
Creating the map document
Before publishing a linear referencing service (LRS), you must use ArcGIS Pro to create a map document that contains at least one LRS Network or an event layer.
Publishing a Linear Referencing-capable map service in ArcGIS Pro
After you create and save your map document with symbology using ArcGIS Pro, you can create the map service with linear referencing capability.
When publishing the resource in ArcGIS Pro, make sure the Linear Referencing check box is checked
Using the service
A map service with linear referencing capability can be used to build web-based and connected mobile linear referencing apps. In addition, ArcGIS Event Editor consumes your data from this type of map service.