Explain the following in CICS:
a.) MDT
b.) Maps

a) MDT :
Modified Data Tag. The bit in the byte of attribute indicates modification of field on the screen. The modification happens on an input operation. Application program receives the data based on the flag of the field. The attributes / fields can be set or reset by using FSET and FRSET operations.

FSET : MDT is set to ensure that the field is transmitted. It happens only on an output operation
FRSET : MDT is reset. The field is continued to be sent until it is reset.

b) Maps :
BMS – Basic Mapping Support has the ability to change the flags from 0 to 1 at the time of modification of the field. If the same map is utilized multiple times, it is mandatory that the flag must be reset to Zero.

Data transmission may happen when PF key is pressed.
Data transmission will not happen when PA key is pressed
MAPONLY is used to send the map alone, without data. Ex – used in menu screens
DATAONLY is used to send data alone, without resending the screen layout. Ex – used to refresh screen d