These are the definitions that I find useful. This is for Media Monkey v2.5.5 with Magic Nodes v1.3b. There are later versions in test but these are both stable.
This one creates a node sorted by Composer for Classical Genre’s only.
Composer|icon:top level|child of:artist|filter:genre in ('classical', 'opera', 'operetta')\<composer>\<album and artist>
The standard Media Monkey Artist includes all the artists on every track (and maybe composers as well). This creates a note with only the whole album artists.
Album Artist|icon:top level|child of:artist\<album artist>\<album|sort by:max(year)>
Finaly, this one is useful to sort out the various formats and bit rates so you can see which ones need replacing.
Encoding|icon:bottom level|child of:year|show tracks:no\<format>\<VBR>\<bitrate>