This update will be live tomorrow (about 16 hrs). Just wanted to write this up to get it out of the way.
/subject resources we include
component_subject_ids, which point to subjects which compose the primary subject in question. Vocabulary has kanji components. Kanji has radical components. Radicals do not have components.
The update will add
amalgamation_subject_ids. You can kind of think of it like the reverse of
component_subject_ids. The attribute lists subjects which has the primary subject as a component.
Radicals are an amalgamation element of many Kanji (if you look at a subject page, such as this one), its analogous to the “Found in Kanji” list.
Kanji are an amalgamation element of many Vocabulary (if you look at a subject page, such as this one), its analogous to the “Found in Vocabulary” list.
Vocabulary are not an amalgamation element of anything.