DDS for display files
Use this file- or record-level keyword to specify that the function key
specified in the keyword (CA01 through CA24) is available for use. It
is to be used as a command attention (CA) key. No input data is
transmitted from the device. Response indicators 01 through 99 are
valid.
Refer to Appendix B, System/36 environment considerations for display files, for special considerations when specifying the CAnn keyword
in files that are used in the System/36 environment.
The format of the keyword is:
CAnn[(response-indicator ['text'])]
If you specify this keyword and the display station user presses the
specified function key, the following happens:
- All other function key response indicators in the input buffer are set off
(hex F0).
- The response indicator, if specified with the CAnn keyword, is set on (hex
F1).
- The OS/400 data management feedback area is updated.
- Data already in the input buffer remains unchanged except that the
response indicator (if specified) is set on.
- Control is returned to your program.
If you specify a response indicator and the key is pressed, the response
indicator is set on and returned to your program. (The text information
is associated with the indicator and is used by high-level language compilers
to help in program documentation.)
If the display station user presses a function key and you have not
specified it as either a command function (CF) key or a command attention key,
the OS/400 program displays a message to the display station user indicating
that the key is not valid at that time.
You can use combinations of CA and CF keywords within the same display
file, but you cannot specify the same key number as both CA and CF
keys. For example, CA02 and CF02 are not valid in the same display
file.
- Note:
- File level CA and CF keys are extended to the record level. This must
be considered when assigning key numbers. For example, if CA02 is
specified at file level and CF02 is specified at record level, CF02 is an
error.
If you specify a key in the range 1 through 9, you must supply the leading
zero in the keyword (for example, CA04).
Option indicators are valid for this keyword.
Validity checking:
When the display station user presses a CF key, the data from fields with
their MDT set on is placed into the input buffer before validity checking is
done. Any errors in the data are then detected, and the appropriate
error messages are sent to the display. Because validity checking is
not done until after the data is placed in the input buffer, pressing a valid
CA key after the CF key can cause incorrect data to be returned to your
program. This condition is not a problem as long as your program does
not process the input data when the CA key is pressed.
This condition can be prevented in either of two ways:
- Do not allow the use of CA keys. Specify CF keys, which cause
validity checking to be done on the data.
- Do not specify any of the following validity checking keywords if CA keys
are allowed:
CHECK(M10)
CHECK(M11)
CHECK(VN)
CHECK(VNE)
COMP (EQ, NE, LT, NL, GT, NG, LE, GE)
RANGE
VALUES
Function keys valid for command attention keys at processing
time:
As a general rule, the last output operation determines which function keys
are valid. However, the following are exceptions to this rule:
- When an operation sends no data to the display, the validity of various
function keys is not changed. Such operations include:
- An output operation to a subfile record
- An update to a subfile record
- An output operation to a subfile control record that only clears, deletes,
or initializes a subfile without displaying the subfile or the subfile control
record
- An output operation that displays an error message by selecting ERRMSG
(Error Message) or ERRMSGID (Error Message ID) can also select a CA or CF key
to be valid while the error message is displayed.
- If MNUCNL (Menu Cancel), MNUBARSW (Menu Bar Switch), or SFLDROP (Subfile
Drop) is specified for a subfile, the validity of the CA or CF key specified
for the SFLDROP keyword is determined by the last output operation.
However, as long as the subfile is displayed, the CA or CF key, when valid,
acts only as a Drop key.
- If SFLFOLD (Subfile Fold) is specified for a subfile, the validity of the
CA or CF key specified for the SFLFOLD keyword is determined by the last
output operation. However, as long as the subfile is displayed, the CA
or CF key, when valid, acts only as a Fold key.
- If two subfiles using SFLDROP or SFLFOLD are displayed at one time, the
same function key should be specified on both the SFLDROP and SFLFOLD
keywords. If they are different, only the key specified for the most
recently displayed subfile is in effect. Pressing the function key
affects the subfile containing the cursor. If the cursor is not
positioned in a subfile, the function key affects the upper subfile.
- If two subfiles using SFLENTER (Subfile Enter) are displayed at the same
time, the only CA or CF key in effect as an Enter key is the CA or CF key
specified for the SFLENTER keyword on the most recently displayed
subfile. The cursor position at the time the Enter key is pressed
determines which subfile is affected.
- Note:
- The following keywords function like CA keys: CLEAR, HELP, HOME, and
PRINT (with response indicator specified).
Example:
The following example shows how to specify the CAnn keyword.
|...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
00011A CA01(91 'End of Program')
00012A CA02(92)
00013A CA03
A
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