For many years, when we used a word-processing application, files were stored in a format that was fully understood only by the application we used. WordPerfect stored WordPerfect files, Microsoft Word stored Word files, and so on-and, while developers often included ad-hoc support for their competitors' formats, that was a hit-and-miss thing, vulnerable to changes in the proprietary formats. The same went for presentation slides and spreadsheets. We all have experience with the results of this, with the difficulties in exchanging files between different applications. OpenDocument format (ODF) is an XML-based open standard file format for office documents such as these. ODF is application-, platform- and vendor-neutral, and thereby facilitates broad interoperability of office documents.