cheat sheets.

rdf: http://www.w3.org/1999/02/22-rdf-syntax-ns#
rdfs: http://www.w3.org/2000/01/rdf-schema#
owl: http://www.w3.org/2002/07/owl#
foaf: http://xmlns.com/foaf/0.1/
dc: http://purl.org/dc/elements/1.1/
doap: http://usefulinc.com/ns/doap#
sioc: http://rdfs.org/sioc/ns#