XForms 1.1 Implementers encouraged to enable multiple MIP bindings per data node

Dear Forms Community,

It is a pleasure to inform you that the W3C Forms Working Group recently 
decided upon a default combination mechanism for handling multiple model 
item properties binding to the same data node. For reference, please see 
[1, 2]

[1] http://www.w3.org/MarkUp/Forms/wiki/MIPS
[2] http://www.w3.org/2010/03/25-forms-minutes.html#res_multimip

For some MIPs like calculate, more than one formula binding does not make 
sense, so the default in that case continues to be an 
xforms-binding-exception.  However, for other MIPs, and most notably 
constraint, it is not only possible but also preferable to have a default 
combinator based on the MIP.  For example, if more than one constraint MIP 
is applied, then all constraints must be satisfied (true) for the node to 
be valid (in fact, this is consistent with current combination processing 
of constraint, required and type MIPs anyway).  By comparison, a node 
would be readonly if any bind readonly MIP evaluates to true for the node, 
and this is conceptually what already happens in the defaulting mechanism 
for readonly, which makes a node readonly if any ancestor evaluates to 
true even if the readonly MIP for the node itself is false.

For these technical reasons and also to promote faster adoption and 
determination of any problems with the approach, the W3C Forms Working 
Group also resolved (see [3]) to encourage implementers of XForms 1.1 to 
proceed with relaxing the xforms-binding-exception for selected MIPs and 
instead use the default combinators as described in [1].

[3] 
http://lists.w3.org/Archives/Public/public-forms/2010Apr/att-0002/2010-04-07.html#resolution1

Best regards,
John M. Boyer, Ph.D.
STSM, Lotus Forms
Workplace, Portal and Collaboration Software
IBM Victoria Software Lab
E-Mail: boyerj@ca.ibm.com 

Blog: http://www.ibm.com/developerworks/blogs/page/JohnBoyer
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