The page Type of text, general keywords, other taxonomies page in the Guidelines should be split into separate pages if different kinds of keywords (such as Material) are to be discussed here. The core page on type of text needs to whittle down to a single proposal, rather than three, and give concrete examples. (This also needs to be implemented in the Reference Stylesheets once applied.) See also discussion in [feature-requests:#133].
@sarcanon Do you still plan to implement this by September 2020? (Or shall we reassign to milestone:future, and/or to another developer?)
Text Type now has its own page along with other descriptive data from header. Committed with revision 2777.