SECTION 5.6
449
Composite Fonts
KEY
TYPE
VALUE
WMode
integer
(Optional)
A code that determines the writing mode for any CIDFont with
which this CMap is combined. The possible values are 0 for horizontal and 1
for vertical. Default value: 0.
The value of this entry should be the same as the value of
WMode
in the
CMap file.
UseCMap
name or
stream
(Optional)
The name of a predefined CMap, or a stream containing a CMap,
that is to be used as the base for this CMap. This base allows the CMap to be
defined differentially, specifying only the character mappings that differ from
the base CMap.
CMap Example and Operator Summary
CMap files are fully documented in Adobe Technical Note #5014,
Adobe CMap
and CIDFont Files Specification.
The following example of a CMap stream object
illustrates and partially explains the contents of a CMap file. There are several
reasons for including this material here:
•
It documents some restrictions on the contents of a CMap file that can be
embedded in a PDF file.
•
It provides background to aid in understanding subsequent material, particu-
larly “CMap Mapping” on page 453.
•
It is the basis for a PDF feature, the
ToUnicode
CMap, which is a minor exten-
sion of the CMap file format. This extension is described in Section 5.9,
codes in this encoding can be either 1 or 2 bytes in length. This CMap could be
used with a CIDFont that uses the same CID ordering as specified in the
CIDSystemInfo
entry. Note that several of the entries in the stream dictionary are
also replicated in the stream data.