The interface block diagram is a traditional systems engineering block-and-line diagram representing the logical interfaces that connect components within a system or system segment. If you are using a legacy schema (pre v90), CORE displays implied and "rolled up" connections based upon lower-level model details as well (this was discontinued in CORE 9 in favor of decomposable interfaces). While extremely powerful, this can often become overwhelming. Sometimes, it’s important to focus just on the current design level. The level 0 variant focuses exclusively on the current design level without considering these computed interfaces.
The level 0 interface block diagram is available for elements in the Component class (as well as any other subclasses of ImplementationUnit).
The only difference between the level 0 interface block diagram and the standard interface block diagram is that the joins thru relationship is ignored when determining which interfaces to display. To help visually differentiate the level 0 variant, no decorations are shown on the interface lines where they connect to the component nodes.