What’s new in SysML 1.5 – Miscellaneous

The third and last part of the blog post series about the changes of SysML 1.5 covers several minor updates.

Reception compartment

Now SysML explicitly defines a block compartment for signal receptions. It is the same notation as in UML. The following figure depicts an example of the reception compartment.

Signal reception compartment of a block in SysML 1.5

Requirement compartments

The SysML specification mentions that requirement relationships could also be depicted in compartments. But the notation was not explicitly defined, yet. Now SysML 1.5 provides a notation for the several requirement relationships compartments. The following figure from the SysML 1.5 specification depicts the compartments. Some relationships are links between requirements (e.g. derive requirement), other relationships link a requirement with a named element (e.g. a satisfy relationship from a block (=named element) to a requirement).

Requirement relationship compartments in SysML 1.5

ntent/uploads/2017/05/named-element-compartment-sysml-1.5-300×242.png” alt=”NamedElement compartments for requirement relationships” width=”300″ height=”242″ /> NamedElement compartments for requirement relationships[/caption]

Changes for ISO 19514

SysML is also an ISO Standard. To conform to the regulations of ISO, some editorial changes were made to SysML. For example, a reference to the ISO 15288 standard and a note that SysML uses the definition of the terms “system” and “systems engineering” as defined in ISO 15288.

More precisely, these were no changes for SysML 1.5, but for SysML 1.4.1. This minor update of SysML was published to enable the publication of SysML as an ISO standard. You find the ISO/IEC 19514:2017 standard here: https://www.iso.org/standard/65231.html

Show units of properties and values

SysML 1.5 provides a notation for units of value properties and values. If the value type of a property has a unit defined, the unit symbol or name could be displayed in parentheses behind the value type.

Unit notation of value property

Values of a value property could also display the unit, if available, behind the value, but without parentheses.

Unit notation of a value

Notation for nested properties

SysML provides a notation for the path name of nested properties. The following figure depicts an example of a nested structure.

Nested structure

The path name syntax of the value property perf in the block Control unit is compA.sx.cu.perf. Assume that the properties of the subsystem and the control unit have no name. In that case, the path name is compA…perf. To avoid such useless notation, SysML 1.5 allows to show the type of a property if the name is not set, i.e. now in our example, the path name is compA.:Subcomponent X.:Control unit.perf.

This blog post was the last one of the blog post series about the changes in SysML 1.5.