-----Original Message-----
From: Martin Bjorklund [mailto:[email protected]] 
Sent: 25 February 2016 15:17
To: William Ivory <[email protected]>
Cc: [email protected]
Subject: Re: [netmod] Clarification needed for YANG 1.1 XPATH context

William Ivory <[email protected]> wrote:
> Hi,
> 
> I'm looking for clarification on the meaning of the following 
> paragraph in section 6.4.1 (XPATH context) in RFC6020bis:
> 
>    'If a node that exists in the accessible tree has a non-presence
>    container as a child, then the non-presence container also exists in
>    the tree.'
> 
> It's unclear to me what this is trying to say, and why - for example, 
> does this mean that I need to validate any 'must' and 'when'
> statements on the child container even when nothing within that child 
> container is configured?

must expressions are always evaluated if the node where the must expression is 
defined exists, regardless of the number of children this node has.

[wivory] So in my example where the child container (non-presence) has NO 
children, then it doesn't exist, and any must statement on it should not be 
run.  Only when a non-presence container has a non-zero number of children 
should any 'must' statements on that container be run.

[wivory] If that's the case, then would it be correct to say that the intention 
of this paragraph is as a reminder that one must evaluate 'must' statements on 
nodes that have no inherent meaning and exist only because they contain child 
nodes?

Thanks,

William


/martin

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