CosArrayCos arrays are one-dimensional collections of objects accessed by a numeric index. Array indexes are zero-based. An array's elements may be any combination of the Cos data types.
 CosBooleanCos boolean objects can have a value of true or false.
 CosDictA Cos dictionary is an associative table whose elements are pairs of objects:
 CosDocA CosDoc object is the Cos layer representation of an entire PDF file. See the PDF Reference for an overview of PDF document structure. See Section 3.6.1, "Document Catalog", in the PDF Reference, for a description of the catalog dictionary.
 CosFixedFixed numbers may only be in decimal format. See Section 3.2.2 in the PDF Reference for details.
 CosIntegerIntegers may be specified by signed or unsigned constants. See Section 3.2.2 in the PDF Reference for details.
 CosNameA name is a sequence of non-white space characters. In code, a name is preceded by the forward slash (/) character indicating that it is a string literal, for example: /AName. See Section 3.2.4 in the PDF Reference for details.
 CosNullThere is only one NULL object, which is used to fill empty or uninitialized positions in arrays or dictionaries. See Section 3.2.8 in the PDF Reference for details.
 CosObjA CosObj is a general object in a PDF file, which may be of any Cos object type. The Cos layer provides methods that are not specific to any particular object. Several methods are available to manipulate a Cos object.
 CosObjCollectionThe CosObjCollection is an opaque structure representing a set of Cos objects associated with a particular Cos document. The initial value of a variable of type CosObjCollection is undefined. Use CosNewObjCollection() to create a collection.
 CosStreamA stream is a sequence of characters that can be read a portion at a time. Streams are used for objects with large amounts of data, such as images, page content, or private data a plug-in creates. A stream consists of these elements, which are listed in their relative order in the stream object, starting at the beginning. See Section 3.2.7 in the PDF Reference for a description of the stream object.
 CosStringA string is a sequences of characters, enclosed in parentheses. See Section 3.2.3 in the PDF Reference for details.
 Encryption_and_DecryptionThe Cos layer provides methods to encrypt and decrypt data in arbitrary memory blocks. The encryption and decryption uses Acrobat's built-in algorithm (RC4 from RSA Data Security, Inc.) and a key that can be specified.
 General General Cos layer objects.