[ZFS] Units of /proc/spl/kstat/zfs/z/txgs

Anyone knows what are the units of ndirty, nread and nwritten in /proc/spl/kstat/zfs/z/txgs?
I have made a simple plugin for netadate to monitor /proc/spl/kstat/zfs/z/txgs, but the units of ndirty, nread and nwritten elude me.

I have moved the topic to the correct category for troubleshooting