This field-level keyword, when specified for a numeric, input-capable field, enables your program to distinguish when the field is blank and when the field is zero on the display. In either case, your program recognizes zeros.
The BLANKS keyword sets on the specified response indicator when the field is blank on the display. After an input operation, your program can test this indicator to determine that the field (whose program value is zero) is actually blank on the display. The field can contain all blanks (hex 40) or all nulls (hex 00). It still appears blank to the display station user. If the indicator is off, the field is zero on the display.
This keyword is also valid for character fields, but there is generally no need to specify it for them. Your program can test character fields directly to determine what is on the display.
See the System/36 environment considerations for display files topic for special considerations when you specify the BLANKS keyword in files that are used in the System/36™ environment.
BLANKS(response-indicator ['text'])
The response indicator associated with the BLANKS keyword should be unique within the record. That is, the same response indicator should not be used with other keywords, such as CHANGE, DUP, or VLDCMDKEY; with any of the keywords for function keys; or with the BLANKS keyword on other fields in the same record. This is because the i5/OS™ operating system always turns the response indicator off if the field contains non-blank characters on an input operation. The i5/OS operating system does this to make sure that when the field appears as all blanks, the response indicator is set on, and that when it does not appear as all blanks, the response indicator is set off.
The optional text is included on the list generated at program compilation time to explain the intended use of the indicator. This text has no function in the file or the program other than as a comment. The single quotation marks are required. If you specify more than 50 characters between the single quotation marks, the text is truncated to 50 characters on the program list.
Option indicators are not valid for this keyword.
The following example shows how to specify the BLANKS keyword.
|...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
00030A QTY1 5Y 0B 5 2BLANKS(01 'ON=QTY1 IS ALL BLANKS')
00040A QTY2 5Y 0B 6 2BLANKS(02 'ON=QTY2 IS ALL BLANKS')
00050A QTY3 5Y 0B 7 2BLANKS(03 'ON=QTY3 IS ALL BLANKS')
A
Three numeric fields (QTY1, QTY2, and QTY3) are displayed. If the display station user types values into the fields and presses the Enter key, the following situation occurs:
| Value as typed into fields | Value as passed to program | Condition of response indicator |
|---|---|---|
| 100 | 00100 | Off |
| 0 | 00000 | Off |
| Blanks | 00000 | On |
Note: If the
display station user presses a Field Exit key or the Erase Input key, the
field appears blank because it contains nulls.
|
||
In some cases, the BLANKS keyword does not set the specified response indicator on but rather restricts its function. Examples 2, 3, and 4 in this topic, illustrate these cases.
In the following example, when an input/output field contains all blanks (hex 40) or all nulls (hex 00) when displayed, and certain keywords affecting the display of the field are also specified, the response indicator is not set on.
|...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
00010A* When OVRATR is specified
00020A R REC1 PUTOVR
00030A FLD1 10 0B 2 2BLANKS(50) OVRATR
00040A 78 DSPATR(HI)
00050A* When PUTRETAIN is specified
00060A R REC2 PUTRETAIN OVERLAY
00070A FLD2 10 0B 2 2BLANKS(50)
00080A R REC3 OVERLAY
00090A FLD3 10 0B 2 2BLANKS(50)
A PUTRETAIN
A
For all record formats in this example, response indicator 50 is set on as expected the first time the field is read by the program (if the field appears blank on the display). However, after a subsequent display, response indicator 50 is set on again only if the display station user again blanks the field. If the workstation user does not again blank the field, response indicator 50 is off.
Examples 2 and 4 concern cases when the field is first displayed, then deleted.
In the following example, when an input-capable field is overlapped by another field, causing the first field to be deleted, the response indicator is not set on (even though the field in the input buffer still contains all blanks or all nulls).
|...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
00010A R REC4 OVERLAY
00020A 15 FLDA 10 0B 2 2
00030A FLD4 10 0B 2 5BLANKS(50)
A
In this example, if option indicator 15 is off when REC4 is first displayed, FLD4 is displayed and FLDA is not. When REC4 is read, response indicator 50 is set on if FLD4 is blank. If option indicator 15 is then set on when REC4 is displayed again, FLDA overlaps FLD4 and deletes it. Response indicator 50 is then off when REC4 is read. (This occurs because the i5/OS operating system turns it off when displaying the record format and does not turn it back on for a field that is not on the display, even if the field contains blanks or nulls from a previous I/O operation.)
In the following example, after initial display, an input/output field is not displayed again on a subsequent input/output operation (even though the field in the input buffer still contains all blanks or all nulls).
|...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
00010A R REC5 ERASEINP OVERLAY
00020A 20 FLD5 10 0B 2 2BLANKS(50)
00030A*
00040A R REC6 ERASEINP OVERLAY MDTOFF
00050A 20 FLD6 10 0B 2 2BLANKS(50) DSPATR(MDT)
A
In this example, if option indicator 20 is on when REC5 or REC6 is first displayed, FLD5 or FLD6 is displayed. When REC5 or REC6 is read, response indicator 50 is set on if FLD5 or FLD6 is blank. However, if option indicator 20 is set off on a second display, FLD5 or FLD6 is not displayed.