Query: data query language 
The query language is a powerful domain specific, declarative scripting
language that can:
	-  list drawing objects, layers and networks
	
-  iterate over them
	
-  evaluate complex logical expressions using them
	
-  selecting/unselecting/printing or drc-reporting objects depending on the result of the evaluation.
This chapter describes the query language and its use. The chapter is
split up to multiple sub-chapters: