A batch mode is a state associated with each step of a batch, with rules that apply up and down the recipe hierarchy. The DeltaV system lets operators control the mode of steps at each level with two commands:
Manual - This command causes the mode of the selected step to go to MAN. In MAN mode, transitions of the immediate subordinate level are prevented from executing until the operator changes the mode back to AUTO. Alternatively, the active step change is enabled. Switching to MAN mode allows the batch to complete its current subordinate step (lower levels remain in an automatic mode, either P-AUTO or O-AUTO).
Automatic - This command causes the mode of the selected step in MAN mode to go to O-AUTO mode (Operator Auto). If the step is running, subordinate transitions are allowed to execute until the step is complete.
You can consider the Batch Mode as the mode of the top level of the Batch. If this is not automatic (that is, O-AUTO), the batch will not complete automatically.