Appendix E. Questionnaire on the "Definitions and Usages" Terminology of SysML v2

The purpose of this questionnaire is to collect anecdotal evidence in favor or against the new "definitions and usages" terminology of SysML v2 by contrasting it with an alternative, more classical terminology. Please try to answer it without being biased in any way.

The following table provides an overview of the two terminologies:

Question 1

Consider the following model sketch about car wheels being composed of a rim and a tire having a size and a load index attribute where the size of a tire is described with the help of three parameters: (rim) diameter, width and height.

Which of the following two model descriptions do you find more readable/comprehensible/usable?

1. The part definition Wheel has two part usages: (1) rim defined by the part definition Rim and (2) tire defined by the part definition Tire. The part definition Tire has two attribute usages: (1) size defined by the attribute definition TireSize and (2) loadIndex defined by the attribute definition Integer (predefined in a SysML2 library). TireSize is an attribute definition with three attribute usages: diameter, width and height, all of them defined by the attribute definition LengthValue (predefined in a SysML2 library).
2. The part class Wheel has two part properties: (1) rim typed by the part class Rim and (2) tire typed by the part class Tire. The part class Tire has two attributes: (1) size typed by the data type TireSize and (2) loadIndex typed by the data type Integer (predefined in a SysML2 library). TireSize is a complex data type with three attributes: diameter, width and height, all of them typed by the data type LengthValue (predefined in a SysML2 library).

Question 2

Consider the following fragments A-C extracted from the SysML2 specification in their original form in item 1 and in their alternative formulation in item 2.

1. From Section 7.11.2 on parts.

   1. Original: Because the base usage of a part usage is the part usage parts defined by the base part definition Part, every part usage is always directly or indirectly defined by at least one part definition, implicitly if not explicitly, in addition to any other item definitions.
   2. Alternative: Because the base property of a part property is the part property parts typed by the base part class Part, every part property is always directly or indirectly typed by at least one part class, implicitly if not explicitly, in addition to any other item class.

2. From Section 7.12.1 on ports.

   1. Original: A port usage is a kind of occurrence usage definition that is a usage of a port definition.
   2. Alternative: A port property is a kind of occurrence property that is typed by a port class.

3. From Section 7.12.1 on ports.

   1. Original: The features of the port usages (whether inherited from its definition or declared locally for the usage) specify what can be exchanged in such interactions. Since ports are themselves kinds of occurrences, port definitions and usages can contain nested port usages.
   2. Alternative: The features of the port properties (whether inherited from its class or declared locally for the property) specify what can be exchanged in such interactions. Since ports are themselves kinds of occurrences, port classes and properties can contain nested port properties.

Which of the two formulations of fragments A-C is more readable/comprehensible?

1. the original formulation
2. the alternative formulation

Area of Expertise

Which is your main area of expertise?

1. Aerospace Engineering
2. Automotive Engineering
3. Mechanical Engineering
4. Electrical Engineering
5. Civil Engineering
6. Industrial Engineering
7. Software Engineering