Pathway

Definition: A set or series of interactions, often forming a network, which biologists have found useful to group together for organizational, historic, biophysical or other reasons. Usage: Pathways can be used for demarcating any subnetwork of a BioPAX model. It is also possible to define a pathway without specifying the interactions within the pathway. In this case, the pathway instance could consist simply of a name and could be treated as a 'black box'. Pathways can also soverlap, i.e. a single interaction might belong to multiple pathways. Pathways can also contain sub-pathways. Pathways are continuants. Synonyms: network, module, cascade, Examples: glycolysis, valine biosynthesis, EGFR signaling

Source:http://www.biopax.org/release/biopax-level3.owl#Pathway