The columns this sub-type renders (#939) — headers + per-row cells.
The injuries in this section, in the order supplied.
Localized subtype label shown in the section legend.
The --ledger-cols grid-template value for this sub-type's ledger (#939).
The subtype key (e.g. "injury"), used to seed new trauma items.
A subtype-labeled section of injuries (traumas), ready to render.