[U-Boot] question about environment variables

Hello

(1) I don't quite understand what README means about CFG_MONITOR_BASE -- is it supposed to reflect the actual physical address, where u-boot resides, i.e. either flash or SDRAM, or it deals with flash only? Why I'm in doubts, because some targets in include/configs/<boards> do not define this macro.

(2) do I understand right that when CFG_ENV_IS_NOWHERE defined, environment variables are not changeable and always default values are used.?

Thanks in advance!