Horizontal balancing ensures that the data entering data stores, AND connectors, and XOR connectors also leaves those objects. The concept of horizontal balancing is not appropriate for processes, in which the data is transformed; different data leaves a process than enters it.
The Balance Horizontal command performs three balancing checks. To run the Balance Horizontal report, select one symbol of these types, and then click Reports > Balance Horizontal.
AND and OR connectors
The data flows entering a connector are balanced against the data flows coming out at the element level. The system tests for the conservation of data rule: Everything going into a connector must come out, and everything coming out must have gone in.
Data stores and their attached flows
Each data store must be entered in the data dictionary, and it must be defined in terms of structures and elements. Any data flow coming into the data store is checked to ensure that all structures and elements it carries are contained somewhere in the data store definition (incoming elements must have a place to park). Similarly, any data flow leaving the data store has its structures and elements checked for matches in the data store definition (outgoing elements must come from somewhere).