[knot-dns-users] Knot 1.5 - what does state "idle" mean?

I'm running 1.5.0-rc1. Here's a question: # knotc zonestatus | grep idle 25.93.in-addr.arpa. type=slave | serial=0 | idle | DNSSEC signing disabled 48.31.in-addr.arpa. type=slave | serial=0 | idle | DNSSEC signing disabled 49.31.in-addr.arpa. type=slave | serial=0 | idle | DNSSEC signing disabled 164.86.in-addr.arpa. type=slave | serial=0 | idle | DNSSEC signing disabled 165.139.in-addr.arpa. type=slave | serial=0 | idle | DNSSEC signing disabled 209.193.in-addr.arpa. type=slave | serial=0 | idle | DNSSEC signing disabled What is the meaning of the "idle" status? It would be good if the output of "zonestatus" were explained in detail (in the man page of knotc or in the manual, or both), along with an explanation of all the various states that a zone can be in. Regards, Anand