Definition of logical design

1. the design of an electronic circuit using logic gates. See gate and cross-references there.
2. the design of the logic of a computer program (as opposed to its user interface or data files).
3. the practice of designing a document by using tags to indicate the function rather than the appearance of each element. For example, chapters are labeled as such rather than just being indicated by words typed in a particular arrangement on the page.

Logical design is the approach followed by LATEX, SGML, and XML; it is not followed by WYSIWYG word processors. Logical design is generally superior for complicated documents because decisions about the appearance of elements of the document can be made independently of the text. If you want to change the appearance of chapter headings, for instance, you need to make the change in only one place because all chapter headings are recognized as instances of the same unit. In a WYSIWYG system, you would need to change each heading individually because the computer does not know that they are alike. Documents with tags specifying the logical design are also easier to handle effectively in computer databases.