StartElement

STARTELEMENT is a term used in XML processing to denote the opening tag of an element, and in streaming XML parsers it also refers to the corresponding event generated when that tag is read. An XML element begins with a start tag, such as <book>, and may include a namespace, attributes, and other metadata that apply to the element. The start element signals the parser to begin constructing the element’s context, which may influence namespace resolution and attribute handling.

In streaming XML APIs, such as SAX and StAX, STARTELEMENT is exposed as a distinct event or callback. In SAX, the startElement method is invoked when a start tag is encountered, providing information about the element’s name, namespace URI, local name, and attributes. In StAX, the StartElement interface represents the corresponding event and provides access to the element’s qualified name, namespace, and a collection of attributes and namespaces.

Key characteristics of a start element include its name (often a namespace-qualified name), and its attributes and namespace declarations that apply to the element. The start element is typically paired with an end element, which marks the end of the element’s content. A self-closing tag, written as <tag/>, is conceptually equivalent to a start element immediately followed by an end element.

In parsing workflows, the start element is followed by zero or more content events (characters, child elements) and then an end element event. Understanding start elements is fundamental to XML processing, as they define the hierarchical structure of the document.