Architecting and designing : DoDAF : DoDAF 1.5 Activity Based Methodology (ABM) : Developing operational views with DoDAF ABM : ABM syntax rules : At least one OV-5 activity model child diagram must be of same type
  
At least one OV-5 activity model child diagram must be of same type
While it is permissible to create a child diagram of any Operational Activity in an OV-5 Activity model from any other type, such as OV-6a Op Rules, there must be at least one child diagram of the same name and of the same OV-5 Activity Model type.
The following images show a valid and invalid example.
See also
ABM syntax rules