"Black Widow" Years/Codes

[stantheboltactionman]

Newbie Question,
I am sure this has been covered before somewhere on this forum...But I am getting too old and lazy to find it!!

Q: What are the years and codes of the so called "Black Widow" Luger?

Q: Can any Luger within the correct years/codes with black bakelite grips
be considered a "Black Widow"?

Q: Is there a certain suffix/Block that is assigned to the so called "Black Widow"?

Just curious, as to why "Black Widow" type Lugers sell for more than their walnut gripped cousins.
Thanks,
Stan