Setting compile flags for only debug build, only for specific tool

From: quarendont (tomq_at_[hidden])
Date: 2005-02-23 10:32:54

I can set compile flags for a particular toolset with
<toolset>msvc:<cxxflags>/YX"stdafx.h"

And I can set compile flags for debug build, verses only release
builds with
<variant>debug:<cxxflags>whatever

However I can't work out how to do both together, that is set a
compile flags for the debug build of a specific toolset. 
I've tried

<toolset>msvc:<variant>debug:<cxxflags>/YX"stdafx.h"

and I've tried 
<toolset>msvc<variant>debug:<cxxflags>/YX"stdafx.h"

but neither seem to work.
How can I achieve this?