> Section 2.4.4.3
> There is formal syntax in this section without any reference to which syntax 
this is. Please include such a one.

OK, I would therefore propose the following text:

<proposed mod>
   The EKU field indicates one or more purposes for which a certificate
   may be used.  It is an essential part in authorization.  Its syntax
   is described in [RFC5280] and [ISO.9834-1.1993] and is as follows:

         ExtKeyUsageSyntax  ::=  SEQUENCE SIZE (1..MAX) OF KeyPurposeId

         KeyPurposeId  ::=  OBJECT IDENTIFIER 
</proposed mod>