Can tuples be used in XBRL linkbases?
Yes. Tuples are defined as elements in taxonomy schema documents and can be referenced from within linkbases in a manner identical to that used for items. Note that tuples do not make sense in all taxonomy linkbases. In particular, they do not make sense in calculation linkbases. However, it is most appropriate, to attach labels and reference information defining the information that tuples are intended to convey using taxonomy linkbases.