[Explanation] agents and services must be able to locate a proposal in this location [Feature/Operation] 
the HTTP extension mechanism
p r o p I D
t h e H T M L L I N K t a g
t h e H T T P e x t e n s i o n m e c h a n i s m
p r o p U R I
X M L p a r s i n g
d a t a r e f e r e n c e s y n t a x
a b s t r a c t e l e m e n t s
h a r m o n i z e d v o c a b u l a r y