behavior of new functions XLOOKUP and XMATCH

[Regina Henschel]

Hi UX-experts,

the new function XLOOKUP and XMATCH have a Match_mode with values 0, 1, 
-1, 2 and a Search_mode with values 1, -1, 2, -2.
The Match_mode 2 means wildcard mode, that is ? * search or regular 
expressions search. The Search_modes 2 and -2 mean binary search in a 
sorted array.

Combining parameter values for wildcard mode and binary search is 
possible. But there exist no way to actually do it. Excel gives an error 
messages in such cases. LibreOffice silently switches to linear search.

The ODF TC is currently working on the specification for these new 
functions. The TC could either follow Excel's way or LibreOffice's way. 
 From a developer state of view it is no large effort to change the 
current behavior of LibreOffice. The TC does not know yet whether 
Microsoft would be willing to switch to LibreOffice's behavior.

I write to you for to get your opinion what will be the best solution 
from a _user_ point of view.

Some arguments so far:
* No error message would make use of the functions in macros and forms 
easier.
* No error message might be better for using the functions in 
automatically calculations without UI.
* Using linear search can be unexpected slow on a huge Lookup_array. An 
error message makes the problem visible to the user.

I would love to hear your opinion.

Kind regards,
Regina