What does rwk stands for?

I just check /etc/apparmor.d/usr.sbin.mysqld

I saw,

/var/lib/mysql/** rwk, // what is rwk stand for ? Is it read, write?? then what does k stands for?
/var/log/mysql/ r,

What does rwk stands for?

Solution

As documented under File permissions:

r - read - permission to read data

w - write - permission to create, delete, write to a file and extend it
[ deletia ]
k - lock - permission to lock a file, is combined with write perm to determine if it has permission to take exclusive lock