Proposal for enhanced cell content validatition

Hi all,

the current specification does not have a feature to specify the content
that is allowed for a cell as an list of possible values. Since this a
feature that is support by several spereadsheet applications, I would
like to propose to enhance the <table:content-validation> element as 
follows:

a) the table:condition attribute (that takes an XPath like expression) 
supports the new function "cell-content-is-in-list(List)", where "List" 
is a ";" separated list of string values.
b) a new "table:display-list" attribute, that my have the values "none", 
"unsorted" or "sorted-ascending", specifies whether or not the list of 
possible values is displayed in the UI wile entering a cell value, and 
if so, whether or not the list is sorted.

In fact, a) may not require a specification change, because we did not 
specify what the values of the table:condition attribute should look 
like exactly, but only by example. However, it might be reasonable to 
enhance this example (or maybe to make the example condition syntax 
normative).

Best regards

Michael