Informative spec: 1.1 Terminology

[agarny]

• 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".
• The "W3 MathML namespace page" should probably point to https://www.w3.org/1998/Math/MathML/ rather than https://www.w3.org/TR/MathML2/chapter4.html#inferf.namespace, which uses an anchor that doesn't exist.
• 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.