WTF?!

PHP use one standard but those Symfony guys use another?!

You may wonder why the helpers are named according to the underscore syntax rather than the camelCase convention, used everywhere else in symfony. This is because helpers are functions, and all the core PHP functions use the underscore syntax convention.
ref: http://www.symfony-project.org/book/1_0/07-Inside-the-View-Layer#chapter_07_sub_helpers