What is SGML in the grand scheme of the universe, anyway?
SGML defines a strict markup scheme with a syntax for defining
document data elements and an overall framework for marking up
documents.
SGML can describe and create documents that are not dependent on
any hardware, software, formatter, or operating system. Since SGML documents
conform to an international standard, they are portable.
How is SGML and would you recommend it to your grandmother?
You can break a typical document into three layers: structure,
content, and style. SGML works by separating these three aspects and
deals mainly with the relationship between structure and content.
Structure
At the heart of an SGML application is a file called the DTD, or
Document Type Definition. The DTD sets up the structure of a document,
much like a database schema describes the types of information it
handles.
A database schema also defines the relationships between the
various types of data. Similarly, a DTD specifies rules
to help ensure documents have a consistent, logical structure.
Content
Content is the information itself. The method for identifying
the information and its meaning within this framework is called
tagging. Tagging must
conform to the rules established in the DTD (see ).
Style
SGML does not standardize style or other processing methods for
information stored in SGML.