Similarly http://www.w3.org/TR/2014/REC-turtle-20140225/#grammar-production-PN_LOCAL

(PN_CHARS_U | ':' | [0-9] | PLX) ((PN_CHARS | '.' | ':' | PLX)* (PN_CHARS | ':' | PLX))?

*However* this has several differences as it allows a leading ':' as well as hex in multiple places.  This matches SPARQL.