The format of ORCHESTRA output can be defined directly in the output file itself, but it is also possible to define output in an external file or object.

To do so just start the outputfile with the definition of a “format” class, and call this class just after it.

The format class is read and interpreted by ORCHESTRA, and rewritten to the output file without changes.

@format(){
   // this format class is literally rewritten in the output file, so 
   // can be used for description of output
   // comment line....
   // another comment line
   // include a central file that contains definition of outputformat
   @include: somefile.txt
   // use the outputformat defined in the central file
   @output_format()
   @output_frequency()
}
@format()

Within the format class, include: statements and comment lines can be used.

This makes it possible to define the required output variables in a central location, which can be useful in case multiple output files are written for may variables (transport systems with many substances).