PATH Mac OS 8 and 9 Developer Documentation > Text Encoding Conversion Manager
Programming With the Text Encoding Conversion Manager

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The Unicode Converter

This section describes the Unicode Converter, which you can use to convert between any available non-Unicode text encoding and the various, supported implementations of Unicode. For background information on Unicode, the problems it addresses, and the standards bodies responsible for its emergence, see About Unicode and Appendix B. For definition of some of the terms used in this section, see Character Encoding and Other Concepts Fundamental to Text Encoding Conversion .

The Unicode Converter does not itself incorporate any knowledge of the specifics of any text encoding. Instead, it uses loadable, replaceable mapping tables that provide the information about any text encoding required to perform the conversion.

All information about a particular coded character set used in a text encoding is incorporated in a mapping table. A mapping table associates coded representations of characters belonging to one coded character set with their equivalent representations in another and accounts for the various conditions that arise when coded representations of characters cannot be directly mapped to each other.

The Unicode Converter can also handle conversions between Unicode and text encodings that use a packing scheme.

To convert text using the Unicode Converter, you must create a Unicode converter object, which references the necessary mapping tables and maintains state information. Because each Unicode converter object is discrete, you can retain several objects concurrently within your application, one for each type of conversion you need to make.

The Unicode Converter supports multiple encoding runs. An encoding run is a continuous sequence of text all of which is expressed in the same text encoding; a given string might contain multiple encoding runs, such as a sequence of text in Mac OS Roman encoding followed by a sequence in Mac OS Arabic. The Unicode Converter allows you to convert a single block of Unicode text to multiple runs in other text encodings. For example, you could convert a Unicode string into one that contains both Mac OS Arabic and Mac OS Roman encodings. You might find this useful when preparing text to display using the Script Manager.