grammar - Using "which" without a comma

This is a follow up from this discussion. I am a patent attorney and some standard sentences that we use include this:

The above-recited and other advantages and features of the disclosure
will become apparent by reference to specific embodiments thereof
which are illustrated in the appended drawings."

I assume a comma should be placed before which, but I am wondering if you could help me understand if it is required or optional?

Also, another sentence I came across goes like this:

Device A sends data to device B which then forwards the data to device
C.

Microsoft Word always complains, seeing it as a restrictive clause and demands a comma or changing which to that. Am I correct in not having a comma?

Answer

In the first example, if the "which" clause were restrictive, some advantage that was not illustrated would not be covered by the patent. Since one expects all possible rights to be claimed, the clause should not be interpreted restrictively, and a comma is required.

In the second example, "device B" is the name of a device, so it is a proper reference. Consequently the "which" clause is non-restrictive, and a comma is required. "That" instead of "which" would be ungrammatical.