RE: [tag] Correction: Re: [tag] TA Condition Qualifiers and TADependencies

[stephen.green@systml.co.uk]

>> Example 1:
>> Spec: #2: item X MAY have property Y
>>       #3: if item X has property Y then item A MUST have property Z1
>>       #4: if item X has property Y then item A MUST have property Z2
>>
>> (Z1 and Z2 might, say, be properties somehow related to Y)
>>
>> It might be that the spec writers realize they have to further qualify
>
>> this to help with the conformance issue: What happens when #3 or #4
>> are not satisfactorily implemented?
>>
>> case 1: if #3 or #4 fails then #2 also fails
>
> case 2: if #3 or #4 fails
>> #2 does not necessarily fail because it is optional
>
> <JD> I would assume that the existence of property Y is somethng that
> can be
> Tested in itself. In that case, #2 can be tested independently. But to
> say that a test "fails" for #2 still need be defined... (does it only
> mean that property Y is not there? Because its hard to fail a
> MAY...)</JD>
>

Good point, I badly worded that. Instead I was probably after the possibility
that failing #3 or #4 turns the MAY of #2 into a MUST NOT. That sounds  
unlikely
but in the real world scenario a faulty traffic light at an optional place in
the road becomes forbidden even though the traffic light itself is optional.