Webel: SysML4Mathematica: Convention: A custom SysML ValueType 'Quantity' extends a custom ValueType '_' (representing a Mathematica '_' Blank). It DOES NOT also extend the SysML Real!
Webel: SysML4Mathematica: Convention: A Mathematica Blank '_' (which pattern-matches any Expression) is represented by a custom SysML ValueType '_'
Webel: SysML4Mathematica: Convention: A '$E' in a function name indicates that all parameters (arguments and return) are Mathematica '_' expressions. However, when representing such functions as Activities they may end up getting strongly typed in tools!
