What is a "black" monsignor?

[Cruikshank_s]

I heard this term thrown out in discussion but never heard of it before, it’s supposedly an old nuance of the position that no longer exists, anyone know of its origin and what the term is referring to? I did a google search but no luck

 

[YoungTradCath]

Perhaps one of the lower-ranking monsignors. Ones who might not [have] be[en] entitled to wear an amaranth or scarlet trimmed cassock. Although I don’t know if this even ever existed.

It is also the custom of some monsignors to wear their monsignorial cassocks throughout the whole year, except for Lent, in which they will wear a simple black priest’s cassock without trim.

 

[Chatter163]

Maybe this?

 

[JGMendes4049]

Black monsignori were vicars general and vicars capitular (diocesan administrators), and were protonotaries durante munere, holding the title of monsignor only as long as they were in their offices. As to why they are called black monsignori, here’s Wikipedia:

The only privileges of dress that Pope Pius X granted [the vicars general and capitular] were a black silk fringed sash, black piping on the biretta with a black tuft, and a black mantelletta. As a result of this they were in some countries referred to as “black protonotaries.”

Protonotaries are a type of monsignor, and through the transitive property, you get black monsignori.