accesskey timing specifier syntax

Hi.

I'd like to get some clarification on the syntax for accesskey timing
specifiers.  SMIL 2.0 says:

  An access key value has the following syntax:

    Accesskey-value  ::= "accesskey(" character ")"
                           ( S? ("+"|"-") S? Clock-value )? 

  The character is a single character from [ISO10646].

How do I specify a "tricky" access key, such as Tab?  With this
document:

  <svg xmlns="http://www.w3.org/2000/svg">
    <rect width="100%" height="100%">
      <set attributeName="fill" to="red" begin="accesskey(&#x9;)"/>
    </rect>
  </svg>

the U+0009 character in the attribute will be normalised to U+0020
before the SVG UA ever gets to see it.

Is there a difference between specifying accesskey(A) and accesskey(a)?
What about accesskey(1) and accesskey(!)?  On my keyboard 1 and ! are
on the same key.

What does it mean to use a character that doesn't correspond to a key,
such as accesskey(&#x2622;)?

Which characters must be escaped?  For example, if I want to use the
minus key, would I have to use accesskey(\-), because of the parsing
rules?  Any other characters?

What about keys that don't corrsepond to a character in Unicode, such
as Home?

Maybe key identifiers like those in DOM 3 Events[1] should be used.

Thanks,

Cameron

[1] http://www.w3.org/TR/DOM-Level-3-Events/keyset.html

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