Text is defined in the PDF file format as a display value (normally what you see onscreen) and an extraction value. It is useful to have 2 options because some characters are displayed differently to what you extract (for example fl is one glyf onscreen but two in extracted text).
But did you know you can have an additional value set to show the actual Text enclosed in a Tj command? If you are using MArked Content, the Dictionary can contain a Dictionary value /ActualText which will be used in place of whatever is shown in the Tj command, which is ignored. So if you want to add something different (or just ensure that the value comes out exactly as you want, it is a useful feature. What would you use it for?
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 13 years worth of PDF knowledge and tips, so click here to visit our series index!
IDRsolutions develop a Java PDF library, a PDF forms to HTML5 converter, a PDF to HTML5 or SVG converter and a Java Image Library that doubles as an ImageIO replacement. On the blog our team post about anything interesting they learn about.