Timo Aaltonen Defining Observation Objectives for Reactive and Distributed Systems. 101-113 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2931&spage=101 2003 conf/fates/2003 FATES db/conf/fates/fates2003.html#Aaltonen03