A Comparative Analysis of Information Hiding Techniques for Copyright Protection of Text Documents

Table 1

Unicode special space characters [22, 32].

Unicode Hex code	HTML code	Name	Written symbol
U+0020	 	Space	“ ”
U+00A0	 	No-break space	“ ”
U+200A	 	Hair space	“”
U+2000	 	En quad	“”
U+2002	 	En space	“”
U+2003	 	Em space	“”
U+2001	 	Em quad	“”
U+2004	 	Three-per-em space	“”
U+2005	 	Four-per-em space	“ ”
U+2006	 	Six-per-em space	“”
U+2007	 	Figure space	“”
U+2008	 	Punctuation space	“”
U+2009	 	Thin space	“”
U+202F	 	Narrow no-break space	“ ”
U+205F	 	Medium-mathematical space	“”
U+3000	　	Ideographic space	“ ”