[ibis-macro] Question about the Format List syntax
- From: "Muranyi, Arpad" <Arpad_Muranyi@xxxxxxxxxx>
- To: 'IBIS-ATM' <ibis-macro@xxxxxxxxxxxxx>
- Date: Wed, 7 Mar 2012 19:37:43 +0000
Hello,
This is mainly a question for the authors of the
original IBIS-AMI specification about the syntax
of "Format List".
The editorial committee is trying to figure out the
original intent of the syntax of List. The question
is regarding the first item in the list called
"<typ value>". This is what I see on page 140:
| Format: (default is range)
| Value <value> Single value data
| Range <typ value> <min value> <max value>
| List <typ value> <value> <value> <value> ... <value>
and there seems to be at least two interpretations
for "<typ value>". One interpretation would treat all
entries in the list as "THE list", like this:
(List 1 2 3 4 5 6 7 8 9)
\----------------/
this entire thing
being the "list"
The other interpretation would take the first number
as an indicator for which value in the list should be
used if Default doesn't exist and the user doesn't make
a selection:
(List 5 1 2 3 4 5 6 7 8 9)
| \----------------/
| this thing being
| the "list"
|
\ this value might be a repeated entry from the
"list that follows" to indicate which value
in the list is to be considered if Default is
not defined or the user doesn't make a selection
In the absence of Default, both of these interpretations
would pick the "first item", but note that in the second
interpretation that first item is repeated in the body of
the list. In order to achieve the same outcome as in the
second example without the repetition, one could provide
a list using a different order:
(List 5 1 2 3 4 6 7 8 9)
\----------------/
this entire thing
being the "list"
but visually this is not as appealing or readable. There
are probably many other detail questions and comments about
this, but I would like to get an answer first on what
the authors had in mind when this was written.
My take on this is that what the spec calls the "<typ value>"
was really intended to be the "<default value>". The
problem is that the word "typ" has a completely different
meaning in the IBIS context and mixing those meanings into
the interpretation of Format List ends up with different
expectations and assumptions. I would suggest to replace
| List <typ value> <value> <value> <value> ... <value>
with:
| List <default value> <value> <value> <value> ... <value>
as an editorial change and be done.
A related, but different question is whether we allow
repeated entries in the list. To me it doesn't make
any sense, but the spec doesn't say so. Should that
be allowed, or prohibited?
Yet another question: Is a list supposed to have more
than one values, or can it also have one value? If so,
what is the difference between Format List, or Format
Value?
I would prefer to keep the solution to these questions
simple, so we could resolve this as an editorial change
without having to write another BIRD...
Thanks,
Arpad
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