Re: <fn> and occurence


Kostya Srebriany wrote:

> Hello, All.
> This example is from manual
>     <apply>
>       <fn occurrence="infix"><mo>&PlusMinus;</mo></fn>
>       ...
> but in chap4_1.html said that 'occurrence' attribute may be used only
> with <declare>. 
> In this case we may write just <fn><mo>&PlusMinus;</mo></fn> because
> PlusMinus is listed in dictionary. 

I think the <fn occurrence="infix"> example is an error.  I copies
Stan Devitt and Stephen Buswell on my message, so I hope we get
confirmation.  But I don't think 'occurrence' should be allowed
anywhere except 'declare'.

On the other hand, you examples clearly point out a problem here.  It
would be unbearable painful to have to use <declare>'s to specify how
you want an operator with several forms to be used.  

> So, we may accept the 'occurrence' attribute in <fn>.
> But if I want to write n@ in content murkup (n factorial, but for '!'
> we use '@') I will fail because there is no predefined value 'postfix'
> for the occurrence attribute.
> And second.
> What should we render if we see
> <apply>
>  <fn>
>   <mo>&SomeInfixOrPostfixOperator;</mo>
>  </fn>
>  <ci>x</ci>
> </apply>?
> Should we use the default value occurrence="Function-model" or use
> 'form' of operator?
> I have many more questions on this topic.
> May be someone have FAQ on it? ;-)
> Kostya

I doubt if there is already a FAQ on it.  Perhaps the thing to do is
to start by making a list of examples showing the problems/ambiguities
with the current model(s).  We can look at them assuming either there
is or is not an occurence attribute on <fn>.