Re: [bufrtables] More on table versions

Dear Jeff,

Milan has covered this topic in detail, so I can hardly add anything useful to it. I can only confirm that our current practice of deprecating
descriptors leads to carelessness in specification of the table versions.
Using only one set of tables may lead to producing a BUFR message
containing descriptors that were introduced with higher version than
it is indicated in the message. Or to processing of the data without taking
into account the version number in the message.

The current practice is not based on BUFR regulations, as Milan indicated. I think that it would have to be changed sooner or later, so better sooner
than later.

With best regards,
Eva

On 13 Aug 2008 at 12:08, Jeff.Ator@xxxxxxxx wrote:

Dear Eva and Milan,

I must admit I'm confused now.  While I certainly agree that it's
possible, and perhaps even preferable, to be able to change the
characteristics of an existing descriptor when a table version number is
incremented, I don't recall that we ever formally agreed to adopt this
as the new practice.  Eva, I have read your 3.1.1(1) document, and I do
recall when we previously discussed the problems of these particular
radiation descriptors; however, I don't recall (nor do I see any mention
in the final reports from any of our previous meetings?) where we agreed
to this change in practice.  As you mentioned, in the past we've always
kept existing descriptors frozen and just deprecated and replaced them
with new descriptors whenever subsequent problems were discovered.  And
while I certainly remember past instances where we've discussed the
shortcomings (e.g. Table B classes rapidly filling up) of this type of
approach, I just don't remember where we ever formally agreed to change
it.  I apologize if my memory on this point is faulty, and if that is
the case could you please point me (and the rest of this mailing list as
well!) to any relevant documentation?

Personally, I have no problem with allowing descriptor characteristics
to change between table versions.  I do think it is workable and has
several benefits, which is probably why I didn't object if/when we did
previously agree to this as a group.  In my below email I was only
trying to describe the current policy (at least as I understood it) to
my colleagues on the mailing list.  As you mentioned, the big issue
involved with changing this would be that the Secretariat would now have
to maintain all of the old versions of the tables (and in a
machine-readable format! :-) somewhere on the WMO web server.  Assuming
Joel is agreeable to that, then I believe the majority of my colleagues
here in the U.S. would agree to it as well.

Thanks and best regards,
-Jeff