Which of the following is correct for the ANR (Automatic Neighbor Relationship) function? (Multiple choice)
A . ANR can automatically detect missing neighbors and automatically detect PCI collisions and automatically assess abnormal neighborhood coverage.
B . ANR can maintain the integrity and validity of the neighbor list and reduce abnormal neighborhood switching
C . ANR can avoid manual operations and reduce network operation and maintenance costs
D . ANR is only applicable to the initial stage of network construction.
Answer: ABC