While php-fig aims to be a standards declaring organization and "PSR-4" happens to be the commonly referred name for package-based class autoloading at this point, I'd recommend to use better method and property names, because:

1. Due to the current state of the package classloader proposal, due to a parallel caching related specification proposal, and due to fig's incremental numbering, the actual and final name of the specification might be PSR-5, not PSR-4.
1. Someone, at some point, for some reason, might have the idea that "PSR" wasn't the best acronym to choose and it gets renamed.
1. In day-to-day development work, how many times do you interact with function names à la `doRfc2466()`?  The specification ID is rather off and not really helpful.
1. Naming of methods should follow intention and meaning.  For example, `addPackage()` would make crystal clear that you're adding package-based namespace roots.  
  (whereas "package" refers to the first two parts in a namespace; i.e., the vendor + component name: `\vendor\component\...`)