# Report the beginning of some internal and external XML entities.
	#
	# The reporting of parameter entities (including
	# the external DTD subset) is optional, and SAX2 drivers that
	# report `LexicalHandler` events may not implement it; you can use the
	# `http://xml.org/sax/features/lexical-handler/parameter-entities`
	# feature to query or control the reporting of parameter entities.
	#
	# General entities are reported with their regular names,
	# parameter entities have `%` prepended to their names, and
	# the external DTD subset has the pseudo-entity name `[dtd]`.
	#
	# When a SAX2 driver is providing these events, all other
	# events must be properly nested within start/end entity
	# events. There is no additional requirement that events from
	# `DeclHandler` or `org.xml.sax.DTDHandler DTDHandler` be properly ordered.
	#
	# Note that skipped entities will be reported through the
	# `skippedEntity` event, which is part of the `ContentHandler` interface.
	#
	# Because of the streaming event model that SAX uses, some
	# entity boundaries cannot be reported under any
	# circumstances:
	#
	# * general entities within attribute values
	# * parameter entities within declarations
	#
	# These will be silently expanded, with no indication of where
	# the original entity boundaries were.
	#
	# Note also that the boundaries of character references (which
	# are not really entities anyway) are not reported.
	#
	# All `start_entity` and `end_entity` events must be properly nested.
	#
	# Parameter:
	#
	# * `name`: name of the entity. If it is a parameter
	# entity, the name will begin with `%`, and if it is the
	# external DTD subset, it will be `[dtd]`.
	#
	# SEE: `end_entity`
	#
	# SEE: `sax::ext::DeclHandler.internal_entity_decl`
	#
	# SEE: `sax::ext::DeclHandler.external_entity_decl`
	fun start_entity(name: String) do end