What does that mean of PgIn[ST3P], RdMeta[ST3UP] when use fs_usage in osx

When i use "sudo fs_usage -w -f diskio" in terminal to show disk call status, the call column show something like this: PgIn[ST3P], PgIn[AT3UP], PgIn[S], PgIn[AT1], WrMeta[A], PgIn[AT3U], RdData[ANT3U], RdMeta[ST2], RdMeta[ST3UP], WrData[AT1], ...

What does that mean?


From the fs_usage man page:

CALL The name of the network or filesystem related call, page-in, page-out, or physical disk access.

PgIn and PgOut are page-in and page-out.
RdMeta and WrMeta are reading and writing file metadata.
RdData and WrData are reading and writing to the file.