Silly question: Plain English or Plain Language?

I've got a silly question: which is the better term, Plain English or Plain Language? Or Clear English or Clear Language? That's silly because the answer should be blindingly obvious, considering the topic.

But to me, it's not obvious. I'm thinking...

• Plain Language/English conventions require that in such a case we use the more familiar term, and stick to it.
• In the US and Canada, Plain Language rules.
• In the UK, Plain English seems to be the norm.
• In non-English speaking countries, clear language (translated) seems common.
• In Australia, language and English are found about equally. (For example, DEST.gov.au goes for Plain English, but the Office of Parliamentary Counsel says Plain Language has a broader meaning.)

I'm trying to nut out the reasons people have for choosing one label over the others.

• English restricts the work to the English language? (Surely that's fair enough: initiatives in other languages have their own terms such as Lenguaje Claro or Klarsprk.)
• Language can be more easily perceived to include visual language?
• Language might imply inclusion of other official languages such as Maori and Sign language?
• English is perceived as the property of England, that non-American nation, country and coloniser?
• English refers to the actual language we're talking about, and so is the correct term?
• Plain sounds boring compared with clear.

Why would anybody care? Well, we're about to form a Plain Something organisation in New Zealand and it would be nice, just for once, to name something appropriately first time around.

Meantime, we can watch videos of the US plain language bill hearings on The Center for Plain Language web site.

Image: "PLAIN" in American Sign Language constructed from chart found on Library.Thinkquest.org