PDF pages of the document reside in scattered form across the PDF file and that is why non-linear files are slower as compared to linear files. As mentioned, PDF body is a collection of objects mentioned above. PDF is largely based on PostScript without the control features of programming languages like if and loop commands. Commands issued by Postscript code to generate graphical contents are collected and tokenized in addition to any files, graphics or fonts referred by the document.
All these contents are accumulated to a single file, resulting in composed PostScript output. Text in PDF is represented by text elements which are actually displayed with glyphs from fonts. A glyph is a graphical shape and is subject to all graphical manipulations, such as coordinate transformation. Because of the importance of text in most page descriptions, PDF provides higher-level facilities to describe, select, and render glyphs conveniently and efficiently.
The graphics operators used in PDF content streams describe the appearance of pages that are to be reproduced on a raster output device.
The facilities are intended for both printer and display applications. The graphics operators form six main groups:. Table of Contents Table of Content.
File Body The body of a PDF file consists of a sequence of indirect objects representing the contents of a document. Cross-Reference Table The cross-reference table contains information that permits random access to indirect objects within the file so that the entire file need not be read to locate any particular object. File Trailer The trailer of a PDF file enables a conforming reader to quickly find the cross-reference table and certain special objects.
Arrays of higher dimensions can be constructed by using arrays as nested elements Dictionaries - collection of objects as key-value pairs.
It can have zero entries. Sometimes, though, I have to counter gross misinformation passed as wisdom. Here are those facts. Please… disseminate, copy, email, distribute, blog, tweet, fax, deliver and otherwise present this information to anyone who still thinks that PDF is proprietary! We all do. Let me explain. PDF is a type of electronic document. Close of voting. Proof returned by secretariat. International Standard under systematic review. This may also interest you. New e- takeoff for aviation industry New technologies, from robotics to machine learning, are ushering in a period of rapid change and development.
While the aviation industry is working to reap the benefits of this industrial automation, …. Got a question? Customer care.
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