We have a link for "W3 schools namespace page" and another for "W3 MathML namespace" while it would be more consistent if the latter was for "W3 MathML namespace page".
Special characters: you might want to have that section to read something like (i.e. reference the way each character is actually called in the Unicode site):
• + the plus sign (U+002B);
• - the minus sign or "hyphen-minus" (U+002D);
• . the full stop or decimal point (U+002E); and
• _ the underscore or "low line" (U+005F).
Whitespace characters: may want to read something like (i.e. start a new list of items):
The following whitespace characters are also recognised:
• the space (U+0020);
• the tab or "character tabulation" (U+0009);
• the carriage return or "CR" (U+000D); and
• the line feed or "LF" (U+000A).
Note the use of ";" rather than "," to delimit list items.