[netmod] Re: AD review of draft-ietf-netmod-yang-module-versioning-13 (Document 1 of 3).

[Reshad Rahman <[e-mail]>]

 Hi Mahesh,
We have addressed your comments in rev-14 except for 1 lingering point below (and a couple of nits where we decided not to make the change).
Inline.
    On Tuesday, September 30, 2025 at 04:15:00 PM EDT, Mahesh Jethanandani <[e-mail]> wrote:  
 
 Hi Reshad,
A couple of comments. See inline with [mj]. Once an updated draft is posted with the agreed changes, we can proceed towards IETF LC.



On Sep 11, 2025, at 8:44 PM, Reshad Rahman <[e-mail]> wrote:
 Hi Mahesh,
Thanks for the review and apologies for the delay.
    On Tuesday, August 5, 2025 at 05:46:14 PM EDT, Mahesh Jethanandani <[e-mail]> wrote:  
 
 
<snip>

Section 4.1, paragraph 1
>    Although the previous section indicates that the actual relationship
>    constraints between different revisions of YANG modules should be
>    specified outside of the modules, in some scenarios YANG modules are
>    designed to be loosely coupled, and implementors may wish to select
>    sets of YANG module revisions that are expected to work together.
>    For these cases it can be helpful for a module author to provide
>    guidance on a recommended minimum revision that is expected to
>    satisfy a YANG import.  E.g., the module author may know of a
>    dependency on a type or grouping that has been introduced in a
>    particular imported YANG module revision.  Although there can be no
>    guarantee that all derived future revisions from the particular
>    imported module will necessarily also be compatible, older revisions
>    of the particular imported module may not be compatible.

RFC 7950 in Section 5.1.1 says that when a module is imported without a specific version, it is undefined which revision is used. Given that, specifying an exact version helps. But if implementations always import the latest version, does specifying the minimum version help? I feel that we are not providing a complete context here.

<RR> I'm not getting the part "But if implementations always import the latest version", are you referring to text in this document? Let's say a type we need in an importing module was added on 2025-09-11 in an imported module. If we put "recommended-min-date 2025-09-11", there is no guarantee that the type we need will be present in all revisions in the future since the type could be removed eventually. OTOH if we don't put a recommended min date and get an older version, for sure we will not have the needed type. But I'm not sure I understood your question... Do the examples in 4.1.1 clarify how recommended-min-date is used?

[mj] I think you explained the problem statement better than me :-). Let us take your example above. 
First let us take the case where a recommended-min-date is present, but the imported module has been updated (by a version greater than recommended-min-date) to remove a type. The compile will fail and the user will get an error. If the recommended-min-date is removed, the user will still get the same error, by virtue of it importing the latest version of the module. The added statement therefore does not help.
Now let us take the second case when a recommended-min-date is specified and the importing module has access only to an older version of the imported module. The compile will fail. If the recommended-min-date is removed, the compile will still fail.The only difference will be with the statement present you will know which (min) version of the imported module needs to be present for the compile to succeed. 
The difference between the recommended-min-date and an exact version that RFC 7950 specifies is that the first case is taken care of, meaning if a later version of the imported module removes a given type it does not affect the importing module. The impact to the second case is the same whether the statement is present or not. I am, therefore, questioning the usefullness of the statement.
<RR2> The main case this extension is trying to help with is when the needed type has not been removed and multiple versions of the imported module are available.
Even with the cases above where you mention that the added statement doesn't help, while we do see a compile failure in both cases but the recommended-min-data statement helps narrow down the cause of the failure. So the statement does help...
Regards,Reshad