PDF accessibility policies

Hi All

A favour to ask: I am trying to establish the international policy situation regarding the use of PDF files i.e. the current position in the UK, EU, US...

As far as I am aware no countries explicitly state a requirement around the use of PDF as we do in Australia (http://www.hreoc.gov.au/disability_rights/standards/www_3/www_3.html#s2_3), that being the case I want to try and ascertain their current stance around accessible documents in general.

Have you come across any policies or know where I may find this information - everything I have found so far is a little inconclusive or potentially out of date.

Many thanks in advance
Neil