PDF documents are ubiquitous and therefore need to be accessible to all.
The ISO 32000 standard defines the PDF document format and includes specific features to enable PDF documents to be accessible. For example alternate text can be added to images or tables can be tagged so that they are read correctly by screen readers.
Although ISO 32000 defines functions that can be used to make PDF documents accessible it does not mandate or provide guidelines on their use.
Almost 4 1/2 years ago the PDF/UA (Universal Accessibility) project was set up to create a standard for accessible PDF. ISO has now granted "Approved Work Item" (AWI) status to PDF/UA, the first formal step in the ISO process which ends (we hope) in an ISO Standard for accessible PDF.
To quote from the document submitted to ISO by the project:
'The primary purpose of this International Standard is to define an implementation of ISO 32000-1, known as PDF/UA, that provides a mechanism for representing electronic documents in a manner that allows the file to be accessible.
These goals are accomplished by identifying the set of PDF components that may be used, and restrictions on the form of their use, within conforming PDF/UA files.'
There is already a great deal of understanding about what is required to create an accessible PDF; the creation of this new standard will formalise and in some cases extend this understanding.
The project has also made recommendation for extensions to ISO 32000-1 that are needed to enable full accessibility of PDF.
Moving from AWI to a full standard will take time but I believe the level of formalisation already reached will help to enable organisation to create accessible PDF today.
I have been a member of the PDF/UA committee in the last year and look forward to continuing the work of turning into a full standard.
For more information on PDF/UA, please visit the PDF Standards Wiki http://pdf.editme.com/.