Vocabulary Petri nets

A vocabulary Petri net, VPN, is defined. A colored Petri net is shown to be a VPN with a randomly assessed storage whereas a FIFO net, a VPN operating by the first in, first out discipline. LIFO is, accordingly, a VPN where the storage is accessed by the last in, first out discipline. LFO nets are also shown to be equivalent to Turing machines. Maintainability is defined as a property which ensures boundedness of a VPN, whatever the accessing discipline.