The
ProcessingInstruction
interface represents a "processing
instruction", used in XML as a way to keep processor-specific information
in the text of the document.
No lexical check is done on the content of a processing instruction and
it is therefore possible to have the character sequence
"?>"
in the content, which is illegal a processing
instruction per section 2.6 of [XML 1.0]. The
presence of this character sequence must generate a fatal error during
serialization.
See also the Document Object Model (DOM) Level 3 Core Specification.