PropertyValue
http://www.w3.org/1999/02/22-rdf-syntax-ns#type
http://www.w3.org/ns/prov#value
  • The only clue, and arguably a tenuous one, I can think of is that X is almost never the first letter of a word, plus the tops of glyphs carry more visual weight, plus the X (and notably not the x, which does maintain conventional contrast distribution) has a lateral spacing issue.
http://www.w3.org/ns/prov#wasQuotedFrom
  • typophile.com