The International Organization for Standardization has approved Adobe Systems' widely used PDF (Portable Document Format) as an international standard, and is now in charge of any changes made to the specification.

The format is open and accessible to anyone as ISO 32000-1, the standards body said Wednesday. The standard is based Adobe's version 1.7 of PDF.

PDF, the file format for Adobe's Acrobat software, has long been used as a standard way for people to exchange and view business documents. However, Adobe kept a proprietary hold on the format until it finally succumbed to industry pressure and submitted PDF for standardization in February 2007.

Adobe's move reflected an industrywide trend to standardize broadly adopted file formats to increase interoperability between different applications people use to create business documents.

Microsoft submitted Office Open XML, a proprietary XML-based document format it built for its Office 2007 productivity suite, to the ISO. The ISO approved OOXML on April 1 in a controversial vote that is still being contested by some of the standards bodies that took part in it.

Microsoft had also aimed to include PDF support in Office 2007 but revised that plan at the last minute over a squabble with Adobe. However, PDF support will be added to Office 2007 in a service pack from Microsoft expected to be released early next year.

That update also will add support for Open Document Format for Office Applications (ODF), an XML-based file format that also is an ISO standard. ODF is a rival to OOXML; it became an international standard in May 2006.