Object Flows (Signal vs Value Type vs block)

[cesaralondono92@gmail.com]

Hi,

I am trying to identify a clear delineation as to when to use a signal vs a value type vs a block to type and object flow on an activity diagram, sequence diagram, or IBD.

[beccared09@gmail.com]

I generally favor signals, especially if it's a simple data transfer that doesn't need much definition. Between my computer and the wifi routing is various data and connection request. These don't need much definition and I'll just use a signal.
Blocks are better for an interface that includes a component that needs to be well defined. The interface between me and the amazon delivery guy last week was a computer. That computer is a important part of my model that is getting a BDD, value properties, and such other definition.
I haven't found an instance for value types yet. I know the Sysml 1.6 spec allows for it, but have no explanation for that.