Apologies; my mistake about ~ here.

LL


> On Jul 21, 2026, at 2:01 PM, Carsten Bormann <[email protected]> wrote:
> 
> On Jul 21, 2026, at 22:05, Laurence Lundblade <[email protected]> wrote:
>> 
>> It looks like -19 attempted to use ~ (unwrap) to remove the array grouping 
>> to yield a sequence. But ~ only works on tag numbers, not arrays.
> 
> Let’s clarify that last sentence a bit:
> CDDL was defined before CBOR Sequences were being used more heavily.
> It therefore has no way to describe a CBOR Sequence directly, only single 
> CBOR data items (CDDL types, i.e., sets of data items).
> 
> Unwrapping (~) a CDDL Tag data item gives you the content of the tag, which 
> is another data item (a *type* in CDDL).
> Unwrapping a map or an array gives you a *group*, which you can use to build 
> larger arrays and maps (see example on page 26 of RFC 8610), but which is not 
> a CBOR Sequence.
> Please see Section 4.1 of RFC 8742 for how to handle CBOR Sequences in CDDL.
> Essentially, if you use CDDL to describe an array the content of which stands 
> for a CBOR Sequence, you’ll need to say that.
> “The elements of a C509Certificate form a CBOR Sequence.  Similarly, the 
> subsequence of elements described as the group TBSCertificate form a CBOR 
> Sequence that stands for a similar structure with the issuerSignatureValue 
> removed at the end.” Or so.
> 3.1.12 then says “…the signatureValue is calculated over the CBOR sequence 
> TBSCertificate."
> 
> Grüße, Carsten
> 
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