Re: [netmod] AD review of draft-ietf-netmod-system-mgmt

Randy Presuhn <randy_presuhn@mindspring.com> writes:

...

>>> Let me be more direct.  To exclude, for example,
>>> VT (vertical tab) but at the same time to include
>>> RI (reverse line feed) in the set of permitted
>>> characters seems ill-advised, to say the least.
>>
>>That was the (somewhat arbitrary) decision taken for XML 1.0.
>>And since it is the serialization format for NETCONF, it was
>>quite logical to adopt it for YANG, too.
>
> This has nothing to do with serialization.  This is
> a question of which code points are permitted within
> strings intended for human consumption.

So you are advocating a more restricted string type, rather than more liberal, right? That wasn't clear to me. In this case I tend to agree. It should be possible to find a subset of UCS that satisfies all thinkable needs of network management and yet avoids the dark alleys of Unicode and possible pitfalls for interoperability.

Judging from another ongoing discussion in the JSON WG, it was a very good decision to remove floating-point numbers from YANG.

Lada

>
>>> I hope the rationale for including the C1 controls
>>> (%x80-9F) while quite correctly severely limiting
>>> the C0 controls is documented somewhere.
>>
>>Note that XML 1.1 allows #x1..#x1f, represented as
>>character references.
> ...
>
> That's beside the point.  Permitting a reverse line feed
> (or any of the other C1 controls) in sysContact, while
> prohibiting a vertical tab, makes no sense at all.  See
> http://en.wikipedia.org/wiki/C0_and_C1_control_codes#C1_set
> for an overview of this rogues' gallery of characters,
> and consider whether it's really a good idea to permit
> them for use in labeling interfaces, etc.
>
>
> Note that we took a somewhat different course in defining
> SnmpAdminString in RFC 3411, and this results in a technical
> incompatibility.  RFC 3411 addresses the issue of C0 and C1
> with a mere recommendation: "The use of control codes should
> be avoided."  What this means is that it is perfectly legal,
> though operationally not recommended, for a MIB object with
> syntax SnmpAdminString (not further constrained by the object-
> type's description) to contain code points *prohibited*
> by the RFC 6020 string type.
>
> Randy
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Ladislav Lhotka, CZ.NIC Labs
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