Have you ever seen a PDF file with interactive buttons, text, or links? This is one of my favourite features on the PDF file format because it makes the documents interactive and much more useful. I have even seen someone make a Hangman game using PDF forms…
These interactive elements are PDF forms, and this series of blog articles (under the title Understanding PDF forms) aims to enlighten you about them. How many different types of PDF form are there? What can you do with them? Any limitations or neat tricks you can use? The articles are written for you, so if you have any questions please post a comment and I will try to work them into the articles.
So let me start off with a brief introduction to PDF forms. There are currently 2 main types of PDF form:-
1. The FDF (Forms Data Format) dating back to the beginning of time.
2. An alternative XML based format called XFA (XML Forms Architecture).
FDF is robust and simple so is still in common usage.
FDF was the original format and is well supported. XFA is the newer format which has now been deprecated and removed from the PDF file format. It is not as well supported as FDF.
Although each has its own specification, they both have things like borders, colors etc as you would expect, but they also have actions defined within each, and although some have more options in one format most are available in both, and later in this series we will look into more detail about these differences.
This post is part of our “Understanding the PDF File Format” series. In each article, we aim to take a specific PDF feature and explain it in simple terms. If you wish to learn more about PDF, we have over 20 years worth of PDF knowledge and tips, so click here to visit our series index!