[1] PNML is an XML-based syntax for high-level Petri nets, which is being designed as a standard interchange format for Petri net tools.
PNML grammar is publicly available on its reference site.
The first part of this international standard,[2] provides the mathematical definitions for high-level Petri nets.
It also provides the graphical form definition, known as High-level Petri Net Graph (HLPNG), and its mapping to the semantic model.
As of December 2004,[update] the first part is an international standard.