Tell me the origins of search engine conventions

There are many conventions for search engines, like

Putting double quotes around phrases.
Capitals being case sensitive but lower case not.
Hi, Opal!
The + and - signs denoting mandatory and mandatory not.
And so on.

But when and where did they originate?

These two at least go back to DIALOG searching, one of the biggest online search tools. DIALOG goes back to the 1960s, I don’t know if those conventions do.