Whitespace variants can be matched with a RegEx and are outside the scope of the name of the functions which implies Whitespace not WhiteSpace Variants...
I assist carrol_jhara in the broader definition of Whitespace. See also Wikipedia. Since C# strings are unicode, one can assume that anything manipulating Whitespaces respects the unicode definition of whitespace (26 different characters in total!).
Even Trim respects this, e.g:
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string s = "\n\f\r\t a b c \u202F ";<br />
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Console.WriteLine("'{0}' <-- '{1}'", s.Trim(), s);<br />
results in:'a b c' <-- '
a b c ? '
And since Trim respects it, your example code is fine off!