168317
In 1996 , he introduced the powerful concept of Metadata Reference Link ( MREF ) for associating metadata to hypertext that links documents on the Web , and described an RDF - based realization in 1998 , long before RDF was adopted as a W3C recommendation .
 W3C recommendation
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 W3C recommendation