+ * Zebra is a search engine for structure data, such as XML, MARC
+ * and others. The following chapters briefly describe each of
+ * Zebra major modules/components.
+ *
+ * \section util Base Utilities
+ *
+ * The Zebra utilities (util.h) defines fundamental types and a few
+ * utilites for Zebra.
+ *
+ * \section res Resources
+ *
+ * The resources system (res.h) is a manager of configuration
+ * resources. The resources can be viewed as a simple database.
+ * Resources can be read from a configurtion file, they can be
+ * read or written by an application. Resources can also be written,
+ * but that facility is not currently in use.
+ *
+ * \section bfile Bfiles
+ *
+ * The Bfiles (bfile.h) provides a portable interface to the
+ * local file system. It also provides a facility for safe updates
+ * (shadow updates). All file system access is handle by this module
+ * (except for trival reads of configuration files).
+ *
+ * \section dict Dictionary
+ *
+ * The Zebra dictionary (dict.h) maps a search term (key) to a value. The
+ * value is a reference to the list of records identifers in which
+ * the term occurs. Zebra uses an ISAM data structure for the list
+ * of term occurrences. The Dictionary uses \ref bfile.
+ *
+ * \section isam ISAM
+ *
+ * Zebra maintains an ISAM for each term where each ISAM is a list
+ * of record identifiers corresponding to the records in which the
+ * term occur. Unlike traditional ISAM systems, the Zebra ISAM
+ * is compressed. The ISAM system uses \ref bfile.
+ *
+ * Zebra has more than one ISAM system. The old and stable ISAM system
+ * is named isamc (see isamc.h). Another version isams is a write-once
+ * isam system that is quite compact - suitable for CD-ROMs (isams.h).
+ * The newest ISAM system, isamb, is implemented as a B-Tree (see isamb.h).
+ *
+ * \section data1 Data-1
+ *
+ * The data1 (data1.h) module deals with structured documents. The module can
+ * can read, modify and write documents. The document structure was
+ * originally based on GRS-1 - a Z39.50 v3 structure that predates
+ * DOM. These days the data1 structure may describe XML/SGML as well.
+ * The data1, like DOM, is a tree structure. Each node in the tree
+ * can be of type element, text (cdata), preprocessing instruction,
+ * comment. Element nodes can point to attribute nodes.