IVOA Architecture
  This note describes the technical architecture of the IVOA. The description is decomposed into three levels. Level 0 is a general, high level summary of the IVOA Architecture. Level 1 provides more details about components and functionalities, still without being overly technical. Finally, Level 2 displays how the IVOA standards fit into the IVOA Architecture. 
Christophe Arviset, Severin Gaudet (for the IVOA Technical   Coordination Group)
astro-ph.IM