[OSM-newbies] Is there a Landuse= Mixed option?

[Dave F.]

Hi

My city centre has been mapped using a combination of three areas marked 
as landuse - residential,commercial & retail.
they all clash with each other & look a complete mess.
In some cases they even been joined together making it difficult to amend.

I understand why it happened. As with many cities there's retail at 
ground level with either residential or commercial in the upper floors 
of multi-storey buildings.
Is there a way to tagged a single area as Mixed & the list the different 
uses?

What would be the best way of clarifying this?

Cheers
Dave F.