Definition: A score associated with a publication reference describing how the score was determined, the name of the method and a comment briefly describing the method. Usage: The xref must contain at least one publication that describes the method used to determine the score value. There is currently no standard way of describing values, so any string is valid. Examples: The statistical significance of a result, e.g. "p<0.05".
Source:http://www.biopax.org/release/biopax-level3.owl#Score