Once you have the text tagged, you then must convert it to your target delivery format (e.g., ASCII or RTF).
The many different word processing file formats has generated many different conversion programs. For example, Word for Windows supports the conversion of many different word processing formats into RTF and ASCII. Many word processors also provide utilities to either convert text to RTF or they let you save text in ASCII format. (Understand, however, that you lose all formatting when you save to ASCII.)
All methods of text format conversion involve pattern recognition of some sort. The source file is scanned until a significant pattern is spotted, and then some appropriate action is performed—typically deleting the pattern or replacing all or some portion of it with another pattern. You should investigate the following types of conversion programs:
Specific purpose—these programs automatically convert from one specific format to another. An example would be a WordStar to Word conversion utility. To run one of these, you simply provide the name of the input and output files and let the software run. If you can find or write one of these programs that matches your needs, it will probably be the fastest way to make your conversions.
General purpose—these programs use some sort of look-up table to make conversions. By editing the look-up table, you can control the pattern searched for and what its replacement will be. These programs can support extremely elaborate patterns, but are only as good as your ability to initially recognize and uniquely define those patterns.
Word processors with Search and Replace—a powerful word processor with a strong macro language can often be useful during some stages of text conversion. But it can also be slow and cumbersome if you are working with megabytes of text. Microsoft Word for Windows is an especially powerful example of this category.