Many people need to tag text with these "bar codes" (uniquely identified entities).
This sort of thinking seems to be common in people who like the idea of the semantic Web but who are pessimistic about its implementation. I'm not sure it's going to be the case.
As we've seen happen with other technologies, I suspect we'll see a MetaWeb style approach of "deriving the barcodes" from existing and unformatted content. This will not be a 100% accurate process, but will be "good enough" to make the semantic Web a realistic and large scale underpinning to the next generation of search systems.