It would be great to be able to use fields that require unique values in the Collector app. We are editing a streetlight poles dataset in the field using Collector, and each pole has a unique PoleID. New poles that are added get assigned a new PoleID (by the person manually at this time as auto-number fields are not supported by Collector either). They have a system for assigning numbers but occasionally we get duplicates. It would be helpful if we could constrain the field to only allow unique values within the Collector app. If we set up an index on the feature class in ArcCatalog that only allows unique values it works great in ArcGIS Desktop but is not supported by Collector.