RAL numbers come from
quote[ In 1927 the German Reichsausschuß für Lieferbedingungen und Gütesicherung"
(State Commission for Delivery Terms and Quality Assurance) invented a
collection of 40 colors under the name of "RAL 840". Prior to that date
manufacturers and customers had to exchange samples to describe a tint,
whereas from then on they would rely on numbers.
In the 1930s the numbers were changed uniformly to four digits and the collection was renamed to "RAL 840 R" (R for revised)....]quote - from the current posting on Wikipedia.org ref RAL...
While I don't in general suspect wiki... of being particularly authoritative on most things, they probably have this simple factoid pretty straight?
The colors we've been kicking around - dunkelbraun RAL Nr 45, dunkelgrau RAL Nr 46 - are historic realities. Some sites use just the "Nr." and others add on the "RAL" when speaking of them... I've seen it both ways. Using "RAL" just acknowledges the reality that those colors were standardized and assigned listing numbers (Nr.) under the Reichsausschuss...starting from 1927. "Nr.45 dunkelbraun" is a specific formal name and ID for a standard color under a specific system (RAL) - "Nr.45" otherwise means nothing, if not in the context of the system which established it!
So, by me, it seems intellectually and technically honest to use that full designation RAL Nr. xx, when speaking of an earlier RAL standard color just as we seem to have no trouble using "RAL 7028 dunkelgelb" instead of just 7028 dunkelgelb when speaking of a post-1940 RAL color... but that's just me!
And the old, 2-digit RAL numbers we are kicking around here were changed to 4-digit numbers starting in the late 1930's... the colors did not change.
As tigerman offered above... opening cans of worms. Ugh!
As to what those colors looked like... well, the J & D scans have frequently been offered up as the "holy grail" in this subject. Not all agree. IF you look, for example, at the supposed "signalbraun" which Testor's ModelMasters offers, that surely is far from being "nearly-indistinguishable" from any version of "schwarzgrau" or "dunkelgrau" or even "anthrazit-grau" which any paint maker has supplied... unlike what is clearly suggested by those scans.
And therein lies a little food for thought, by me: it's all possible that Testors' is way way off - not just a wee bit, but WAY so, with both their "signalbraun and any other "dunkelbraun" they offer, or...! So, for those who read any of many sites which identify the brown used in that pre- JULY 1940 2-tone scheme as being "signalbraun" (and many do...) rather then "dunkelbraun Nr.45"... what do you do?
"yous pays your money and yous places your bets", gents! It's a model. Build it. Paint it. Enjoy it - however you do!
Bob