Complex sentence: Petri Net Markup Language (PNML) is an XML-based syntax for high-level Petri nets, which is being designed as a standard interchange format for Petri net tools.
Split into simpler sentences: Petri Net Markup Language (PNML) is an interchange format aimed at enabling Petri net tools to exchange Petri net models. PNML is an XML-based syntax for high-level Petri nets, which is being designed as a standard interchange format for Petri net tools.