What is “Safe Mode” ?

Dear All,
I’m newbie to MikroTik RouterOS, kindly advice for the following.

Q1: What is “Safe Mode” ?
Q2: It will work with all commands or only specific commands?

http://wiki.mikrotik.com/wiki/Manual:Console#Safe_Mode

/ip address print
Flags: X - disabled, I - invalid, D - dynamic

ADDRESS NETWORK INTERFACE

0 ;;; MGT
10.x.x.x/x 10.x.x.x vlan100
1 ;;; This is a test of SAFE MODE
10.x.x.x/x 10.x.x.x ether

Q: why these interface not marked with safe mode Flag?

Safe mode simply means that changes made to the router after safe mode is entered aren’t persisted. If the router loses contact with the session that started safe mode it quits safe mode and rolls back all changes. However, if you quit safe mode manually the changes are committed permanently.

There are no flags to apply to interfaces.

Many thanks , I got my answer.