[Lingo] kanji with the same onyomi

[steve smith <sjs@example.com>]

Some time ago I was told that in some cases groups of kanji have the 
same onyomi and that the onyomi is determined by the right-most of the 
sub-kanji within the kanji.  They had a name for this which I can't 
remember.

At the time I was a bit overwhelmed by trying to remember the kanji I 
knew. Now those teachers are gone and I can't find a reference.

I think an example might be:
壌嬢穣譲醸
all of which have the onyomi of ジョウ.

Does anyone know if this is correct or not?

Thanks
Steve S.