Webel: SysMLv1: Recommend using Block Definition Diagrams as associative, graphical engineering "scratchpads" FOR YOU; Use Internal Block Diagrams as the main presentation diagrams for your engineering colleagues and other stakeholders!

Experience shows that most engineers who are not yet fluent in SysML (and those who don't have past experience with UML) understand Internal Block Diagrams (IBDs) that present a system or device using a port-based "signal processing" idiom far better than the associative graphical notations used in Block Definition Diagrams (BDDs).

Internal Block Diagrams (IBDs) use a representation and modelling idiom that is very similar to electrical circuit design, network design, and mechatronics, and are typically more accessible to a wider audience than BDDs.