In a lot of languages with simple OO capability (PHP 4), or misunderstood OO capabilities (Javascript, C using function pointers, etc.), you'll end up with a function naming convention that uses leading underscores to to indicate privilege level.

//ex.

function _myPrivateFunction(){

}   

While individual teams are always going to come up with their own naming conventions like this, the underscore convention seems so prevalent that it made me curious about

1. Where the technique first came from


2. If there was ever any standardized systems (sort of like hungarian notation) developed around the convention

Beyond pure curiosity, I'm seeing this in a few codebases I'm dealing with right now, and I'd like to understand the possible headspaces of the developers who originally came up with it.