ymlpp preprocesses YML files to produce either flat YML or GraphViz dot files.
ymlpp is part of the SESAME software system. More information can be found on the web at http://sesamesim.sourceforge.net/.
variable=value pairs can be used to pass parameters to your simulation at run time. This can be used, for example, to name input files. These variable value pairs are made available to the YML scripting language which in turn can pass the values to application processes via YML properties. See the YML Users Guide for more information.