Inconsistent TLV specification

[tuve]

• OMA-TS-LightweightM2M_Core-V1_2-20201110-A_full (and all previous versions)
• section 7.4.5

In table 7.4.5-1, the Type field, bits 7-6 states:

10= multiple Resource, in which case the Value contains one or more Resource
Instance TLVs

further down on the page you find:

When a Multiple Resource has to be returned to the LwM2M Server, the Multiple Resource TLV MUST be used whatever
the number of Instances (0, 1 or more) of that resource.

The conflicting part is 'one or more' vs '(0, 1 or more)'. To me it seems clear that the 'one or more' is at fault since it is quite possible to have a multiple resource with no instances e.g., a error codes. Neither can I see any reason why a writable multiple instance shouldn't be writable as no instances, i.e., clearing a multiple instance resource.

Could someone clarify if a multiple resource type must have instances?

[sbernard31]

I agree this is probably an error in specification :

10= multiple Resource, in which case the Value contains one or more Resource
Instance TLVs

Should be

10= multiple Resource, in which case the Value contains 0, one or more Resource
Instance TLVs

[sbernard31]

And probably also :

00= Object Instance in which case the Value contains one or more Resource TLVs

Should also be :

00= Object Instance in which case the Value contains 0, one or more Resource TLVs

(From : http://www.openmobilealliance.org/release/LightweightM2M/V1_1_1-20190617-A/HTML-Version/OMA-TS-LightweightM2M_Core-V1_1_1-20190617-A.html#Table-744-1-TLV-format-and-description)

Even if the use case is less obvious, I guess maybe you can have some Object Instance with no resource at all (if they are all optional) 🤷