SGML as a component of the digital library

Working with documents in electronic format is inherently different from dealing with materials in print; nor can all electronic formats be considered equivalent. Processing and presenting SGML is not the same as processing and presenting materials in other markup or word processing formats. To maximize flexibility and extensibility, SGML is highly modular, which complicates implementation. Its emphasis on content structure rather than appearance enhances searchability but makes consistent and precise display difficult. Mechanisms used to maximize platform and software independence (e.g., entities, link protocols), though effective, can be used incorrectly or in ways difficult to implement on some systems or using certain software. Difficult questions remain for libraries planning to implement SGML.