HP 3000 Manuals HP 3000 Manuals
SCREEN Command
The SCREEN command displays a screen.
Formats
SCREEN {screen_name}
{data_ref }
Parameters
screen_name
The name of the screen to be displayed.
data_ref
May be one of the following containing the name of the screen to be
displayed:
* Constant.
* Variable or calculated item.
* Screen field name.
* Scratch-pad field name.
Description
The SCREEN command displays a screen.
If the screen is a menu, any current process, function, screen, decision
table, or report is terminated immediately.
When HP ALLBASE/4GL starts processing a data screen, the flow of control
in the application is determined by the screen and the logic associated
with the screen. Displaying a screen terminates the current screen (if
one is active) and clears the screen field buffers. The data screen
remains active until the user or the logic associated with the screen
initiates a screen commit action.
When a screen is committed, HP ALLBASE/4GL resumes running the
application in one of three possible ways, depending how the screen was
invoked.
* If the screen was displayed by a SCREEN command in a logic block,
control returns to the command immediately following the SCREEN
command.
* If the screen was displayed directly from a menu, control returns
to the menu.
* If the screen was displayed from a SCREEN command in a function on
a field on another screen, or from a function called from a
function key on another screen, HP ALLBASE/4GL first returns to
the function and executes the remaining commands in the function
logic block. Since the original screen is terminated when the
second screen is displayed, control then returns to the logic
block or menu that displayed the original screen.
NOTE In general, you should avoid calling further data screens while a
data screen is active.
If you need to modify the current screen, use a window in
preference to calling a further screen.
Chapter 6 describes the processing that is performed when HP ALLBASE/4GL
displays a data screen.
Example
SCREEN V-updt_enq
This command displays the screen whose name is contained in the variable
updt_enq.