Two different defs of MAX_TUPLES_PER_PAGE

Hi,

I found two different definitions of MAX_TUPLES_PER_PAGE.
Which is reasonable? Or do they have another meaning?

backend/commands/vacuumlazy.c
#define MAX_TUPLES_PER_PAGE  ((int) (BLCKSZ / sizeof(HeapTupleHeaderData)))

backend/nodes/tidbitmap.c
#define MAX_TUPLES_PER_PAGE  ((BLCKSZ - 1) / MAXALIGN(offsetof(HeapTupleHeaderData, t_bits) + sizeof(ItemIdData)) + 1)

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ITAGAKI Takahiro
NTT Cyber Space Laboratories