Portable Document Format (PDF) is a file format used to present documents in a manner independent of application software, hardware, and operating systems.
PDF file
Every glyf inside a PDF file can have a display value and a different extraction value. This is useful because often you need to... Text is defined in the PDF file format as a display value (normally what you see onscreen) and an extraction value. It is useful... A PDF file are designed to be resolution independent – they are defined using resolution independent units so that the page will always appear... Did you know that PDF files can actually define spaces in several different ways? Three common ways I have found of representing spaces between... When you are viewing a PDF file, you may well notice that (like a web page) there are blue clickable links. These are defined... 
