CITY COMPENSATORY ALLOWANCE (CCA) - to whom it is given, what are the constraints for giving it and how much is given?

Recently CENTRAL GOVT had given A-1 status to Hyderabad (which is included along with 5 other major cities ). And it also issed hike of HRA to central Govt employees and CITY COMPENSATORY ALLOWANCE (CCA).
please clarify :
Explain what is CCA, to whom it is given, what are the constraints for giving it and how much is given?
Also how much HRA will be issued to A1 city CENTRAL Govt employees?and also tell me what are the other benefits do A1 city CENTRAL Govt employees get it?

the maximum limit for CCA is 850 per month and it it given to employees in Delhi and Mumbai.
HRA is 50% of basic for metros and 40% of basic for non metros

Hi we are transferring one of our employee to Bangalore from Delhi for temporary basis, can we add CCA to his salary and what is the max limit, can we remove that allowance once he will back to Delhi.