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Adobe Acrobat SDK
Developing Plug-ins and Applications
Hexadecimal strings
Strings may also be written in hexadecimal form, which is useful for including arbitrary binary data in a
PDF file. A hexadecimal string is written as a sequence of hexadecimal digits (0–9 and either A–F or a–f )
enclosed within angle brackets (< and >). Consider the following example:
<4E6F762073686D6F7A206B6120706F702E >
Each pair of hexadecimal digits defines one byte of the string. White-space characters (such as space, tab,
carriage return, line feed, and form feed) are ignored. If the final digit of a hexadecimal string is missing,
that is, if there is an odd number of digits, the final digit is assumed to be 0. Consider the following
example:
<901FA3>
This is a 3-byte string consisting of the characters whose hexadecimal codes are 90, 1F, and A3, but
<901FA>
Cos arrays
Arrays are one-dimensional collections of objects accessed by a numeric index. Array indexes are
zero-based and may be any combination of the Cos data types. The following array has seven elements:
three integers, a string, a Boolean value, a dictionary (containing one key-value pair), and an indirect
object reference.
[ 1 2 3 (This is a string) true << /Key (The value) >> 6 0 R ]
Cos names
A name object is an atomic symbol uniquely defined by a sequence of characters. Uniquely defined means
that any two name objects made up of the same sequence of characters are identically the same object.
Atomic means that a name has no internal structure; although it is defined by a sequence of characters,
those characters are not considered elements of the name.
/AName
A slash character (/) introduces a name. The slash is not part of the name but is a prefix indicating that the
following sequence of characters constitutes a name. There can be no white-space characters between the
slash and the first character in the name. The name may include any regular characters, but not delimiter
or white-space characters. Uppercase and lowercase letters are considered distinct: /A and /a are different
names. The following examples are valid literal names:
/Name1
/ASomewhatLongerName
/A;Name_With-Various***Characters?
/1.2
/$$
/@pattern
/.notdef
is a 3-byte string containing the characters whose hexadecimal codes are 90, 1F, and A0.
Working with Cos Objects
About Cos object types
181
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