Analytics iteration

In case of only reading the attributes of the tag structure during an analysis/calculation, as tagname, tagnum, etc. could there be a way to put the attribute even though it's an output. Background: Customer is using analysis template where some of the elements do not have the tag used on analysis. So he did an if TagBad('attribute') is true NoOutput(), so does not write anything to the output attribute (that is the same tested), he can do this when it is periodic using trigger time. But when he uses relative time ('*-15m') it gives him the following error: Cannot override output time stamp if any output is used as an input within an analysis. So, he wants the analysis to allow te input as the output even though in same cases (elements) it does not exists.