Hi,
In the documents obtained from the link, they are saying these bits are useful to maintain timing relationship. When it would be required to maintain timing relationship? Can you illustrate with one realtime apllication example.
It depends on the slave device you are using.. Not all slaves in SPI are same.. if you read the device specification of the device you are using then they will mention how the slave have to triggered with respect to polarity and phase.. there are many SPI based ADC, DAC, memory, etc with different specifications.. so it depends on the slave device you are going to use.
how they should be synchronized with master will be defined in the datasheet..