A primer on the Petri Net Markup Language and ISO/IEC 15909-2

ISO/IEC 15909 is an International Standard that is concerned with the high-level Petri nets. Part 1 defines the concepts, the mathematics, and the graphical notation -- and some variants of high-level nets. Part 2 of ISO/IEC 15909, which is currently under the last ballot to be an International Standard, defines a transfer format for high-level nets.

The transfer format defined in Part 2 of ISO/IEC 15909 is (or is based on) the \emph{Petri Net Markup Language} (PNML), which was originally introduced as an interchange format for different kinds of Petri nets. In ISO/IEC 15909-2, however, it is used in a setting restricted to high-level nets and a simple version of Petri nets called Place/Transition-Systems.

Future parts, of PNML will use the generality of PNML and also standardise some of its other concepts. For example, it is planned that Part 3 will define a module concepts known from modular PNML and will make the concept for defining new Petri net types explicit. In this paper, discuss PNML, its relation to ISO/IEC 15909 and the main ideas for the future extensions of PNML and its standardisation in Part 3 of ISO/IEC 15909-2.