This is the Autocad MEP Wishes forum and this question is not really appropriate for this forum. But to answer your question, both Autocad MEP and Autocad Architecture use what is called a mvblock. A mvblock has the ability to use a different block for each view. So for instance, if you are in a 2D view (TOP), you can assign it a 2D block to display. You can then assign it a 3D block to display in you are in an isometric view. I hope this answers your question.
To expand on Keith's response, you can also control each of the 6 views and what block(s) are displayed. So, if you are doing an elevation view, you can create a mvpart that has an elevation block while looking at the front. It doesn't have to be a solid. You can also attach as many blocks you want. I'm sure there's a limit, but I can't see a reason anyone would come close to that limit.
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