Some new input for the hierarchy discussion
Now that I “worked” a bit with the upcoming Open Ethnographer tagging interface, it seems indeed that code hierarchies are not needed to find a tag faster. Its fast auto-complete and some upcoming fine-tuning of it seem to be a nicely-working solution. You basically find a tag by what you remember about a tag’s name. Which means that Ethnographers can still use an informal system of tag name prefixes and postfixes as a mnemotechnique (like, letting tags for specific initiatives begin with "project: "). The advantage over a formal hierarchy is that restructuring ones tags does not mean one has to re-learn their names / way to find them.
This leaves analysis as the realm where tag structures might still be needed. “Tagging a tag” as you proposed earlier is possible with a term reference field in the Drupal taxonomy that stores our tags, is exportable to RQDA (which supports “tag groups” but not hierarchies) and makes sense as “assigning a broader concept” to a tag just as a tag “assigns a concept” to a piece of text, as per the skos:Concept linked data interpretation.
Update: The disadvantage of a prefix / postfix mnemotechnique as proposed above is of course the manual maintenance effort when changes to prefixes / postfixes are required, due to the implied redundancy. If that turns out later to be annoying and decreasing the speed of work to a significant amount, the “tags of tags” can also be included in a way that lets them be found via the auto-complete function. For example:
- tag name "DIY fuels"
- tagged itself with "topic", "grassroots innovation"
- appears rendered as "DIY fuels (#topic, \#grassroots_innovation)" in the auto-complete list
- can be found in the tagger auto-complete field with, for example a "fuel \#topic" search string