i have 1 mapset is there. on that mapset contain four maps are there. i am enter the data in first map,second ,third control is reached the middle for the field in thrid map. on that time i remember to change some fileds in first map that's way i am get back to the first map by using pf keys. the control is goes to previous map. on that time theres is data will be present on the first map fields? how to avoid this situation?
to define a map we can use NMDS,BMS OR SDF
NMDS:means native modes data stream ,we can create maps by using this but this will not support format independence and device independence .
BMS:means basic mapping support ,by using this we can create maps which supports format indepedece as well as device independece.
SDF:means screen defintion facility. by using SDF we can define maps which supports device as well as format independence.
BMS is more useful than NMDS.
WE can create maps using SDF it is like a tool to create maps ther is no need to write the macros like in BMS.
just we need to specify the field names & lengths.
for ur first question
u need to use DFHBMSCA
this should be include in your COBOL program as COPY DFHBMSCA
it holds the values of the field attributes.
by passing appropriate values to the fields you can set /reset the fields dynamically.
coding in the SEND MAP command as ERASEAUP which will erase the unportected fields in the map