[1] XLIFF 1.2 Representation Guide for HTML (2008-01-03 05:12:05 +09:00 版) <http://docs.oasis-open.org/xliff/v1.2/xliff-profile-html/xliff-profile-html-1.2-cd02.html#SectionDetailsElements>

Element	Inline?	Empty?	PCDATA?	Mixed?	Wrapper?	Status	Type Value (ctype if inline, restype otherwise)
SYMBOL	inline			mixed		RobotHelp	x-html-symbol

[2] Document Structure – SVG 1.1 (Second Edition) ( (2011-08-10 12:35:27 +09:00 版)) <http://www.w3.org/TR/2011/REC-SVG11-20110816/struct.html#SymbolElement>