Link groups allows the logical organization of phases within a recipe in order to facilitate communication and synchronization of those phases. Once grouped, the phases either request a message from or submit a message to the group. How each phase sends, receives and uses that message is determined by the logic written in the individual phase logic modules.
Link groups can only occur between phases that are in the same recipe level. If the current recipe level is an operation, the only valid phases for link groups are other phases in that operation. If the current component is a unit procedure, the valid phases for link groups are other phases found in any operation referenced by steps in the unit procedure. If the current component is a procedure, the valid phases for link groups include:
This means that the number of valid phases for a link group becomes greater the higher up the recipe component hierarchy you go. You can create a link group from any phases that are referenced (either directly or by drilling down into the components) by the recipe.
Any phase used in a link group must be based on a phase class with a number of partners greater than zero (0).