Corrections to A Menagerie of Timed Automata
  This note corrects a technical error in the ACM Computing Surveys paper mentioned in the title. The flaw involved constructions for showing that timed automata with urgent locations have the same expressiveness as timed automata that allow false location invariants. Corrected con- structions are presented in this note, and the affected results are reproved. 
Jeroen J.A. Keiren, Peter Fontana, Rance Cleaveland
cs.FL