PCML consists of the following tags, each of which has its own attribute tags.
- The program tag begins and ends code that describes one program
- The struct tag defines a named structure which can be specified as an argument to a program or as a field within another named structure. A structure tag contains a data or a structure tag for each field in the structure.
- The data tag defines a field within a program or structure.
In the following example the PCML syntax describes one program with one category of data and some isolated data.