Just a note about nomenclature or the names of these various Elmars. Please correct me if I am wrong.
50mm 3.5 LTM mount was called Elmar and coded ELMAR. This is the original classic lens in all its variations. '30 - '59
50mm 3.5 M mount was called Elmar and coded ELMAM / 11110. This is quite a rare lens made between '54 and '61. One doesn't hear much about it but I understand it is very good, as you would expect. Ergonomically it is similar to ELMOM below.
50mm 2.8 LTM mount was called Elmar and coded ELMOO. '57 - '62
50mm 2.8 M mount was called Elmar and coded ELMOM /11112. '57 - '74
Note that none of the above are called 'Elmar M' or 'Elmar-M'
Then in 1994 the M6J kit comes along with a different 50mm 2.8 Elmar in M mount called Elmar-M.
The M6J Elmar-M is optically the same as what was to become the Elmar-M but with the addition of a focussing tab that looks like an infinity lock, a mount that looks more 'traditional' and a chrome 'beauty ring'. It is chrome only and and I do not know its code. There are other variations with different engravings for limited editions.
In 1995 the Elmar-M is introduced. Chrome 11823 and black 11831. No focussing tab etc etc. Again there are limited editions.
The point that I am labouring with is that the original M mount Elmar (ELMOM) is not called Elmar-M, that name only applies to the post 1994 lenses.
...retires to darkened room exhausted...