CHAPTER 1
26
Introduction
this book. Implementors of PDF producer and consumer applications can use
this information as guidance.
This edition of the
PDF Reference
describes version 1.7 of PDF. (See implementa-
ular versions of PDF is marked with indicators such as
(PDF 1.3)
or
(PDF 1.4).
Features so marked may be new or substantially redefined in that version. Fea-
tures designated
(PDF 1.0)
have generally been superseded in later versions; un-
less otherwise stated, features identified as specific to other versions are
understood to be available in later versions as well. (PDF consumer applications
designed for a specific PDF version generally ignore newer features they do not
recognize; implementation notes in Appendix H point out exceptions.)
Note:
In this edition, the term
consumer
is generally used to refer to PDF processing
applications;
viewer
is reserved for applications that implement features that inter-
act with users. This distinction is not always clear, however, since non-interactive
applications may process objects in PDF documents (such as annotations) that rep-
resent interactive features.
The rest of the book is organized as follows:
•
the design considerations behind it, compares it with the PostScript language,
and describes the underlying imaging model that they share.
•
ment level. It sets the stage for subsequent chapters, which describe how that
information is interpreted as page descriptions, interactive navigational aids,
and application-level logical structure.
•
appearance of pages in a PDF document.
•
form of character shapes, or glyphs, defined by fonts.
•
tions are matched to the characteristics of a particular output device.
•
model, introduced in PDF 1.4, in which objects can be painted with varying
degrees of opacity, allowing the previous contents of the page to show through.