Inductive indexSemanticT : Set :=
  (** Indices represent a list of line segments. *)
  | INDEX_SEMANTIC_LINE_LIST
  (** Indices represent a list of line segments (strips). *)
  | INDEX_SEMANTIC_LINE_STRIP
  (** Indices represent a list of triangles. *)
  | INDEX_SEMANTIC_TRIANGLE_LIST
  (** Indices represent a list of triangles (strips). *)
  | INDEX_SEMANTIC_TRIANGLE_STRIP
  (** Indices represent a list of triangles (fan). *)
  | INDEX_SEMANTIC_TRIANGLE_FAN
  .
