proces state '<' and 'N'
 

As I know, in the result of ps, '<' means the process is a high-priority prcess and 'N' means the process is a low-priority process. However,I wonder how to distinguish high priority from low priority. Is there a absolute standard?

From the man page:
which I interpret as
The nice value is a parameter of the kernel's scheduling algorithm used to calculate processes' priorities. By default, a process has a nice value of 20.

Thank you，it helps