4. With regard to labelling it was pointed out that in some cases labelling was mandatory as such; in other cases it was not mandatory to label products but if labels were used they had to conform to certain requirements (conditional labelling); in yet other cases labelling was not subject to regulations (voluntary labelling). There were two types of mandatory requirements; in the first it was mandatory to show certain information and in the second it was mandatory to present information in a certain way.
This note is along the same lines:
37. Requirements in the field of packaging and labelling may be mandatory or voluntary. For example, in the case of some products, it is mandatory to label a product. The mandatory obligation may be of two types; it may be obligatory to show certain information on the label; it may be obligatory to present information in a certain way. In other cases it may not be mandatory to label a product, but if labels are used they are required to conform to certain requirements (conditional labelling); in some other cases labelling may be purely voluntary, inasmuch as it is not required under any regulation.
So now we've got a third category, "conditional labelling," that seems to be neither mandatory nor voluntary. Does this affect the analysis of whether measures like the tuna labelling one are "technical regulations"?
Of course, the "conditional labelling" discussion deals with whether the labelling requirement is mandatory, not whether compliance with the "document" is mandatory as set out in TBT Annex 1, so it's a little different.