iPXE-specific options description

[The_Immortal]

Hello!

I'm wondering where can I find a detailed description about iPXE-specific options (http://ipxe.org/howto/dhcpd):

option space ipxe;
option ipxe-encap-opts code 175 = encapsulate ipxe;
option ipxe.priority code 1 = signed integer 8;
option ipxe.keep-san code 8 = unsigned integer 8;
option ipxe.skip-san-boot code 9 = unsigned integer 8;
option ipxe.syslogs code 85 = string;
option ipxe.cert code 91 = string;
option ipxe.privkey code 92 = string;
option ipxe.crosscert code 93 = string;
... etc.

I don't understand what do they mean just by looking at their names...


Thank you!