What the actual difference of A4 and A5 events in the LTE Handover ?

Question

I was going through the measurement configuration sends from eNodeB to UE in RRC Connection Reconfiguration message.
I saw that multiple events have been defined and are used. Couple of parameters are considered to detect entering and leaving condition of an event for example event A1. Now I have a question "Threshold and Hys values are same for all the cell or it may different". Does the standard define the value of all these parameters or network operator defines ? If network operator does then what are points to derive these values ?

Answer 1

Event A4

The LTE Event A4 is triggered when a neighbouring cell becomes better than a threshold.

MEAS(neigh) + O(neigh,freq) + O(neigh,cell) - Hyst > Threshold 

Triggering of the event is subsequently cancelled when the following condition is true:

MEAS(neigh) + O(neigh,freq) + O(neigh,cell) + Hyst <Threshold

Event A5

LTE Event A5 is triggered when the serving cell becomes worse than threshold-1 while a neighboring cell becomes better than threshold-2. The event is triggered when both of the following conditions are true:

MEAS(serv) + Hyst < Threshold-1 
MEAS(neigh) + O(neigh,freq) + O(neigh,cell) - Hyst >Threshold-2

Triggering of the event is subsequently cancelled when either of the following conditions are true:

MEAS(serv) - Hyst > Threshold-1     
MEAS(neigh) + O(neigh,freq) + O(neigh,cell) + Hyst <Threshold-2