Prerequisite Concepts
XML/SGML objects

OmniMark provides powerful query facilities for retrieving information about the current SGML or XML context. The following information is available:

• the value of the APPINFO string in the SGML declaration, if specified (only available when processing SGML documents)
• the name of the DOCTYPE element of the current document instance
• the name of any currently open elements
• the attribute values of any of the currently open elements
• the names of any elements which immediately preceded the currently open elements
• the type of content that immediately preceded any of the currently open elements
• the public identifier, system identifier, notation, or the data attributes of any entity referenced by an ENTITY attribute or any currently open element
• the public identifier or system identifier of any notation referenced by a NOTATION attribute of any currently open element
• the name of the current external text or data entity, if any
• the public identifier, system identifier, notation, or the data attributes of the current external text or data entity

In addition, OmniMark also provides:

• a data structure that represents the stack of currently open elements, allowing you to make complex queries about, and to iterate over all open elements
• data structures that represent the declared and specified attributes of each currently open element, allowing you to make complex queries about, and to iterate over the attributes