When using the standard recommended workflows to create your diagram template and schematic feature classes in your schematic dataset; that is, when using the Import From Feature Layers or the Import From Feature Classes/Tables command, the resulting schematic feature classes are created with the same coordinate system as the one on the imported layers/feature classes. So, most of the times, your schematic feature classes and their associated GIS feature classes share the same coordinate system. However, you are right; nothing prevents users to work with different coordinate systems on their schematics and GIS.
To change the coordinate system on your schematics data, you must operate on both the diagram template and all its schematic feature classes as explained in the following topics:
Cautions:
- To prevent unexpected/strange results when applying algorithms on your diagrams afterwards, you must make sure you set the same coordinate system on the diagram template and all its schematic feature classes.
- It is also recommended to change coordinate system on empty schematic feature classes/diagram template tables; that is, we recommend to delete any diagrams that may already exist for your template before changing your diagram template+schematic feature classes coordinate system
