Syntax on RecipientInfo

I believe the following ASN definition is in error:

RecipientInfo ::= CHOICE {
  ktri KeyTransRecipientInfo,
  kari KeyAgreeRecipientInfo,
  mlri MailListRecipientInfo
}

Each choice is a Sequence so shouldn't they be numbered so that it is known
which one is actually chosen?

Michelle Casagni
GTE Internetworking