...
An example where the metadata must be added to in order to maintain Principle 1 is when a questionnaire uses an arrow to denote a condition. It is impossible to document an arrow literally and leaving it out of the documentation altogether changes the logical flow of the questionnaire. Therefore, text representing the arrow's meaning has to be added.
4. Do not allow the data recorded (i.e. the variables) to inform the metadata archiving.
...
The most common situation where breaking Principle 4 is valid is when Principles 2 or 3 must be broken. For example, in the situation where it is most appropriate to correct the questionnaire, it is obviously vital to check whether the mistake was intentional or not and if the mistake had a distinct effect on the collected data.
References
Poynter, W. and Spiegel, J. (2015) Protocol Development for Large-Scale Metadata Archiving using DDI-Lifecycle. IASSIST Quarterly, 39, 3, p.23-29.
...