Layers used in VO can be grouped to four (4) different types:
- Hydrologic Object Layers – Layers that are used to store and display hydrologic objects.
- Support Layers – Layers that provide support functions.
- Base Map Layers – Layers that provide background map data (Available only in ArcGIS).
- Imported Layers – Layers added by users.
Both the Hydrologic Object Layers and Support Layers are system layers and are saved in the project file. They can’t be removed from Table of Content.