PDF is a file format developed by Adobe Systems for representing documents in a manner that is separate from the original operating system, application or hardware from where it was originally created. A PDF file can be any length, contain any number of fonts and images and is designed to enable the creation and transfer of printer-ready output.
Each PDF file encapsulates a complete description of a 2D document (and, with the advent of Acrobat 3D, embedded 3D documents) that includes the text, fonts, images and 2D vector graphics that compose the document. They do not encode information that is specific to the application software, hardware, or operating system used to create or view the document.
Palm Markup Language is a specialist file used to create documents for an application called eReader which is the Palm eBook program. The creator of a PML file can then use another program which then converts the various files into a single PDB or PalmDOC file for use on a Palm Device.
PML files consist of tags used to give structure to the eBook. This allows the creator to define various features of an eBook including Chapters, Paragraphs, Indents, Titles and References. It also permits formatting tags such as Bold, Small Caps and Superscript. It also allows for images to be added to the eBook file.