Selector Syntax #a#b

hi,
should the following selector be valid?

#a#b

Jigsaw parses it as invalid and obviously it does not make sense but if 
I read the Selector spec right it should be syntactically valid?

http://www.w3.org/TR/css3-selectors/#grammar

simple_selector_sequence
   : [ type_selector | universal ]
     [ HASH | class | attrib | pseudo | negation ]*
   | [ HASH | class | attrib | pseudo | negation ]+
   ;

even in http://www.w3.org/TR/CSS21/grammar.html

simple_selector
   : element_name [ HASH | class | attrib | pseudo ]*
   | [ HASH | class | attrib | pseudo ]+
   ;

Should the spec be adjusted or jigsaw?

thanks,
Christof