[odf-discuss] Backwards compatibility and formula specs

[M. Fioretti]

Going with a new thread since this has nothing to do with the current
GNOME/OOXML discussion.

On Fri, Nov 02, 2007 03:59:38 AM -0700, Daniel Carrera
(daniel at zmsl.com) wrote:
 
> Marco wrote:

> > Please elaborate on this. Does this apply also to the creation of
> > NEW spreadsheets? Or is it a problem ONLY with migration of
> > existing ones?  If it applies to new files too, can MS technically
> > patch their product to not create such problems? If not, why not?
> 
> It applies to new documents too. The reason is that the Formula spec
> defines some formulas different from how they are defined in
> Excel. There were some formulas where the developers (we) felt that
> Excel defines formulas wrong.

Since honestly I have had no time before to document myself on this, I
welcome, here or offlist, relevant links to detailed explanation and
examples, thanks. Now:

>Yes, MS can technically patch their product, but they won't because
>that would break backwards compatibility with any existing document
>that depends on the formulas giving the wrong answer. These bugs have
>been known for a long time and MS hasn't patched them to not break
>backwards compatibility.

please hold my hand for a moment, I am surely missing some piece of
the puzzle here. Theoretically, Excel, Calc or any other program can:

1) create new .ods files, or open and edit existing ones, always
   dealing with formulas as per ODF 1.2,

AND, at the same time,

2) Open, save or display .xls files, always dealing with their
   formulas as per "the MS/Excel/OOXML way", whatever that means.

Right?

If yes, doesn't the problem exist ONLY when you want to convert .ods
to .xls or vice versa? Or when you copy and paste a section of a
spreadsheet from an .xls "window" to an .ods one? Because in that
_moment_ you would need an intelligent, maybe very hard to automate
way to convert from one set of formulas to another, otherwise the
receiving _program_ would execute formulas in the wrong way or crash?

(I am *deliberately* ignoring macros until I have this point clear)

Mind you, I'm not saying at all that is an easy or small problem, I'm
just asking if these are THE only "backward compatibility" use cases
that prevent (technically, of course) patching Excel or Calc. 

TIA,
	Marco
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