SYSML16 — The SysML classification of properties is incomplete

SysML 1.3 section 8.3.2.2 Block says:

SysML establishes four basic classifications of properties belonging to a SysML Block or ValueType.
…
A property typed by a SysML ValueType is classified as a value property, and always has composite aggregation.

In SysML, we also have Signals.
In UML, Signals can have properties.

How does SysML then classify properties defined in a Signal?

A very strict reading of the SysML spec would suggest that a Signal cannot have any kind of SysML property because a Signal is neither a SysML Block nor a SysML ValueType.
However, this is clearly too restrictive in practice.

I propose expanding SysML's classification of properties to include SysML Blocks, ValueTypes and Signals.
This leads to another question:

What are the legal types of a property belonging to a Signal?

I propose restricting such properties to be typed by SysML ValueTypes only. This corresponds to the practical situation where a Signal carries a data payload – I.e., it is a message with some data content.
Allowing a property belonging to a Signal to be typed by a SysML Block or Signal leads to semantic problems — what would it mean to send / receive such signals?

Defer

Postponed to the next RTF