Xing headers

[Bluechip]

Is there any reason why the Audio frame which contains the Xing header 
should be at the same sample rate (32K, 44.1K, 48K) as the main Audio data?

That is, (by example) what if my Xing header were in an Audio frame which 
claimed to be at 48K ...but the first _real_ Audio frame (and all 
subsequent Audio frames) are actually 44.1K ...would any-body or more to 
the point any-software complain?

[bitrate can obviously change in a VBR file]

Thanks,

BC