MS_REF_DEFAULTSETTINGS control most of the reference attachmetn settings.

But not one that I find very important: reference default level (see image)

This defines the level of the reference, it is very important when exporting to dwg. If it is not set, the viewport or xref will be placed with the active level.

My idea is for this to be set at the variable, so that all my sheet references or blocks are in the correct level (example of user levels: viewports, default, 0, xref, ..)