This is more of a searching related question, but an excellent thread at Search Engine Watch Forums asks What's Link| Versus Link: Showing On Google? The initial question asked. is the syntax link|www.domain.com an alternative to the link:www.domain.com at Google? That was quickly negated after a few tests. Danny Sullivan offered a guess that the | is seen as a space when conducting a search at Google. But Danny admitted that "it's a mystery" to him as to what the | (pipe) does actually. Member "berneboy" said its obvious to him what it is, he said;
Since pipe is considered as an 'or' command in a whole bunch of programming and query languages, how about google treating it as such.
Which Danny offers a logical explanation as to why it is probably not the OR equivalent. Danny explains that he has "never seen the pipe suggested as an alternative. It could be undocumented." He then logically explained that even if "link|searchenginewatch.com = link OR searchengine.com = link OR searchenginewatch OR com" it would bring back the same results, but none do.
GoogleGuy comes to the rescue and clarifies that "| is the same as OR." He said that "the '|' character is an undocumented way to do an OR." Basically, "[agassi|davenport] is equivalent to the search [agassi OR davenport]." On a more personal note, GoogleGuy explains he likes to use the pipe alternative because "it makes [him] feel smarter."