question about zeroes in the wal file names

[Luca Ferrari <fluca1978@xxxxxxxxx>]

I'm just curious to better understand the naming convention behind wal
files, because I've seen on a system of mine that the wals created
were:

000000050000020E000000FF
 000000050000020F00000000

while I was expecting 20E0x100. So I digged into the code and I've
seen, from the XLogFileName macro, that the last part is built as the
reminder of the number of segments per wal file:

#define XLogFileName(fname, tli, logSegNo, wal_segsz_bytes)    \
    snprintf(fname, MAXFNAMELEN, "%08X%08X%08X", tli,        \
             (uint32) ((logSegNo) / XLogSegmentsPerXLogId(wal_segsz_bytes)), \
             (uint32) ((logSegNo) % XLogSegmentsPerXLogId(wal_segsz_bytes)))


and with the default wal size of 16 MB that gives a remainder of 256
(FF + 1). Assuming I haven't missed anything, this means that there
are 6 zeroes that will never change in the last 8 chars of the wal
filename.  Is therefore this only done to handle PostgreSQL WAL sizes
of 4 GB each?

Thanks,
Luca