About arp.gratuitousrate and arp.gratuitousburst database variables

Hello, I recently checked that the db variable value of arp.gratuitousrate on a device using tmos 10ver is 1. As far as I know, the default value is (tmos 17ver) 0. My question is two things.
First question. What is the meaning of the variable in arp.gratuitousrate? If it is 1, does it send garp one per second? Then what does 0 mean?

Second question. The existing device does not have a db called arp.gratuitousburst (10ver), so what is the role of this db?

Thank you.