In Corticon 5.3.1 , once a ruleflow is executed can I call a different ruleflow ?
One ruleflow cannot call another ruleflow.
A ruleflow is a way of organizing Rulesheets into one single unit. It is a "flow diagram" depicting a set of one or more Rulesheets.
You can model subflows within a ruleflow so that one subflow is called before a second subflow
It is also technically possible to create an Extended Operator (or Service Call Out) which invokes one or more separate rule flows (Decision Services) as if they were just functions. This might be necessary if the second decision service depended on a different vocabulary than the the first or perhaps if the first decision service used rules to determine which of a set of possible decisions should be executed. However its probably just simpler to use your application code (or business process engine) to call both decision services in sequence passing appropriate data from the first into the second.