All add-ons must be distributed free of charge. Developers may not create "premium"; versions of add-ons with additional for-pay features, charge money to download an add-on, charge for services related to the add-on, or otherwise require some form of monetary compensation to download or access an add-on.
Whoosh.
Definitions of certifiable on the Web:
* fit to be certified as insane (and treated accordingly)
* capable of being guaranteed or certified; "a certifiable fact"
wordnet.princeton.edu/perl/webwn
* That can, or that must be certified; Mentally ill to such an extent that involuntary institutionalization is appropriate; crazy
en.wiktionary.org/wiki/certifiable
Living on Earth may be expensive, but it includes an annual free trip around the Sun.