NET/MASTER Network Control Language (NCL) Reference Manual

&SYS.PANEL.MODFLD
System Variables
5–82 106126 Tandem Computers Incorporated
&SYS.PANEL.MODFLD The &SYS.PANEL.MODFLD system variable contains the names of the fields that
have been modified in a displayed panel. The changed fields as a result of being input
fields on a panel are returned in the order they appear on the screen (that is, left to
right and top to bottom).
&SYS.PANEL.MODFLD contains all fields that have been modified, if the FLDCTL
operand of the CONTROL verb has been specified. Fields flagged as being in error or
modified by the SETERR or SETMOD operands of the ASSIGN verb are also returned
by &SYS.PANEL.MODFLD.
&SYS.PANEL.MODFLD can be processed as an ordered list. Any successive reference
to this variable returns the name at the top of the list until it is empty. Such references
include assigning user variables to &SYS.PANEL.MODFLD, as well as referring to
&SYS.PANEL.MODFLD in IF or SELECT conditional statements.
The MODFLD attribute of a field is retained unless it is cleared by the ASSIGN verb
operand OPT=MODFLD or a new panel display. If a field still has a MODFLD attribute
when a subsequent panel is displayed, and that field appears on the panel, it is again
treated as being modified by the user and appears in the &SYS.PANEL.MODFLD list.
This is particularly useful when processing panels that contain selection lists. For
example; the user can be presented with several options in a selection list, only one of
which (say) is incorrectly entered. The panel may be redisplayed to highlight the field
(option) in error. After the second display, the correctly entered options can be
processed through &SYS.PANEL.MODFLD.
&SYS.PANEL.MODFLD
Considerations
An important efficiency consideration: when using panels, the
&SYS.PANEL.MODFLD system variable should be used for field validation. Then
you need only validate what has changed.
See also the ASSIGN and CONTROL verbs in Section 3, “Verbs.”