Encoding

I'm confused by:

****************************
9.1.1. Document Prefix
> 
Note that all documents in a stream must use the same character
encoding. However it is valid to re-specify the encoding using a byte
order mark for each document in the stream.
*****************************

Those two lines would seem to contradict each other. Is it that they
must use the same character encoding unless a BOM precedes the document?
In other words a file (or any other source) must be treated as a
(potential) collection of documents each which may be preceded by it's
own BOM? 

Thanks,
Greg.


------------------------------------------------------------------------------
Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer
Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports
Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper
Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer
http://pubads.g.doubleclick.net/gampad/clk?id=154622311&iu=/4140/ostg.clktrk