[css3-syntax] Percent in Number-rest state

Hi, here's a question about the Syntax Module Editor's Draft 5 January 
2013:

Tokenization:

3.3.16. Number-rest state 
(<http://dev.w3.org/csswg/css3-syntax/#number-rest-state>):

U+0025 PERCENT SIGN (%)
     Emit a percentage token with its value set to the number produced 
by interpreting the number token's representation as a base-10 number. 
Switch to the data state. Reconsume the current input character.

Why is the current input character ('%') to be reconsumed? The result 
is an additional delim token with value '%' emitted in Data state.

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