The same fifty-two bits the single-user format carries, sent over four symbols instead of two.
Sixteen microseconds carrying the same information eight would. The repetition is the mechanism — a receiver that cannot decode one copy cleanly can combine both, which is worth several decibels at the edge of a cell. Note that the bit count is unchanged while the duration doubles: two facts about one field that do not imply each other, which is exactly the case PLAN.md §3.2 built the schema around.
HE-SIG-A
Authored in HE ER SU PPDU . Drawn in 21 frames.