This is a type of software that can create portable documents. This is most typically the Portable Document Format or PDF. These files can be transferred between systems without losing their formatting or graphics. For this to work, two main functions need to be present and supported. First, a program needs to be able to publish the document in the relevant format, and then it needs to be able to display it – this would be a file viewer. These two functions don’t need to be contained in the same program.