NET/MASTER Network Control Language (NCL) Programmer's Guide

System Variables Set by the PANEL Verb
Working With Panels
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using the #OPT ERRFLD statement to display the error message unchanged and place
the cursor on the field in error. In this last case, you can define the ERRFLD operand
in the #OPT statement as ERRFLD=&SYS.PANEL.FLD to simplify processing.
Using this return code is an ideal way of providing an escape mechanism (such as the
F3 function key) even though the panel has been defined as having mandatory input
field (using REQ=YES).
Return Code 12. This return code indicates that the panel display timeout limit specified
by the #OPT INWAIT statement has elapsed without any data entry. The
&SYS.INKEY variable is null. (If input occurs, the timer will not expire.)
Return Code 16. This return code indicates that the panel was not displayed. This can
mean that the panel does not exist or that an error exists in the panel description file.
The &SYSMSG variable contains a message describing the error condition.
Return Codes From
Asynchronous Panels
The return codes in the &SYS.RETCODE system variable from asynchronous panel
display primarily indicate the result of attempting to display the panel.
Return codes are always available in &SYS.RETCODE, regardless of the setting of the
CONTROL [NO]PANELRC.
&SYS.RETCODE can contain a value of 0, 4, 8, 12, or 16, as described below.
Return Code 0
This return code indicates that the display operation has not been performed because
the panel has already been displayed and input is now available from that earlier
display. Internal validation has not detected any errors.
This happens if your NCL process repeatedly updates a panel, but between updates
the operator enters some input into a field on the screen and causes an input operation
by pressing the ENTER key or a function key. The input variables defined for the
panel now contain the updated values as entered by the operator.
You can process the input, but you must reissue the PANEL verb to update the panel
display.
Return Code 4
This return code means the same as return code 0, except no input fields have been
changed, so the operator has only pressed the ENTER key or a function key.
&SYS.INKEY contains the value of the key pressed.
Return Code 8
This return code indicates that internal validation has detected an error in an input
field. The &SYSMSG variable contains the text of the error message: for example,
NOT WITHIN RANGE. The &SYS.PANEL.FLD system variable contains the name of
the input field in error—this is the name of the variable, less the ampersand (&), that
receives data entered into that field.
When this return code is set, the NCL process can ignore the error and take alternative
action: for example, the NCL process can display a help panel, alter the error text