I have a text only pdf by Putts that describes the Leica stable. Unfortunately no lens numbers or diagrams. However he says this for a later version of the Elmarit M (not Tele Elmar which come earlier). Not sure when "today" was mind you ...
"Elmarit-M, 1990 & 2.8/90, Elmarit-R, 1980
In 1980 the Wetzlar designers recomputed the 2.8/90 for the R again and created the
best 2.8/90mm ever in the Leica history (R and M). The first series of the R-version
have been built in Portugal. The M-version arrived on the market in 1990, and is,
even today, one of the best lenses in the Leica M stable. We seem to have reached a
temporary platform here and while the new Apo-Summicron-M Asph indicates the
future direction as far as design methodology is concerned, an upgrade would not be
very cheap."