Ranko Lazic Tom Newcomb Joël Ouaknine A. W. Roscoe James Worrell Nets with Tokens which Carry Data. 251-274 2008 88 Fundam. Inform. 3 http://iospress.metapress.com/content/b81rl42686x233m1/ db/journals/fuin/fuin88.html#LazicNORW08