1. A method comprising: obtaining instructions for a customized function block in a parametric block type, the parametric block type comprising one or more block class definitions; developing, at a parametric block engine, the customized function block based on the instructions in the parametric block type; and executing the customized function block; wherein the parametric block type further comprises a table including one or more operation codes or parameters that represent the instructions for the customized function block, the one or more operation codes or parameters configured to replace at least one input or output of a pre-existing function block with at least one customized input or output of the customized function block.