[DR 300] Requiring XP itself to be layered

DR 300 states:
"The requirements that XP be ... layered ..."
 
whereas the explanatory sentence:
"In this context, layering refers to both ... etc."
 
explains that layering is external to XP itself.
 
I suggest alternative wording:
"The requirements that XP supports use of layering, and be modular,
extensible 
and transport independent imply ... "
 
Regards, 
Yin Leng