Why Stylesheets?

XML is not a fixed tag set (like HTML) and has no (application) semantics

XML markup does not (usually) include formatting information

Reuse: the same content canlook different in different contexts

Multiple output formats: different media (paper, online), different sizes (manuals, reports), different classes of output devices (workstations, hand-held devices)

Styles tailored to the reader's preference (e.g., accessibility): print size, color, simplified layout for audio readers

Standardized styles: corporate stylesheets can be applied to the content at any time

Freedom from style issues for content authors: technical writers needn't be concerned with layout issues because the correct style can be applied later