Contexts are used to pass values amoung variables.
Following screen shows use of context in synon.
There are following types of context in synon
PAR - Parameter context refers to parameters of the current program.
PGM - Program context is used to pull program information like return code, cursor field etc..
JOB - The JOB context contains system fields that supply run time information about the job executing the HLL program which implements a CA 2E function, for example, the user name, the job name and the job start time. The JOB context is fixed and additional fields may not be added to it.
LCL - refers to local variable defined within the program.
WRK - Work variable are visible through out the External function.
RCD - Record context is available in screen functions and refers to Records on the screen.
CTL - Control context is available in screen functions and refers to control field of the screen.
DTL - The DTL context is available in the action diagrams of function types 'Prompt record', 'Edit record' and 'Display record'. The context is only available after the key has been successfully validated.
2ND - 2nd refers to 2nd screen of Edit/Display record function(2 Screen).
3RD - 3rd refers to 3rd screen of Edit/Display record function(3 Screen).
NXT - Next context is used in printer file to refer next printable variables.
CUR - Current context is used in printer file to refer curretn printable variables. KEY - The KEY context contains the fields which are on the key screen display of CA 2E device functions that have key screens; for example 'Edit record', 'Display Record'.
DB1 - The DB1 context contains the file fields which are in the first or only format of CA 2E access path.
DB2 - The DB2 context contains the file fields which are in the second format(if any). The DB2 context is only available in the action diagram of functions which attach to a Span (SPN) access path, namely 'Edit transaction' (EDTTRN) and 'Display transaction' (DSPTRN).
NLL - The NLL context is available at all points in the action diagram of all function types. Its used when you dont want to pass any value to a parameter. Only output parameters may be directed to the NLL context.