Location Field (Columns 39 Through 44) - IBM 5280 Programmer's Manual

2. When a WRITE is executed, any data in the associated record will be
written to the screen. You should therefore ensure that such fields are
either initialized with blanks or the data you want before the WRITE is
executed.
3. The operator can write over any data appearing in the field unless
CHECK(BY) is in effect.
To Prel'ent Entry of Data in a B-Field
To prevent the entry of data in a B- Field, use the CHECK(BY) keyword
described later in this chapter. With this keyword, you can cause the cursor to
bypass a field on the screen either conditionally or unconditionally.
Location Field (Columns 39 through 44)
In the location field, you code the location where the field will appear on the
screen as follows: you specify the line number (vertical position) in columns
39-41 and the horizontal position in columns 42-44. The actual line where the
data appears on the screen depends on whether or not you specify the
STARTING AT LINE
n
clause in the corresponding WRITE statement in
your COBOL program. Here are the rules that determine which line a field
will appear on:
1. To determine the physical line on the screen, add the STARTING AT
LINE value with the value you write in columns 39-41. Then subtract 1.
2. If
you don't specify a STARTING AT LINE clause, the default value will
be 3.
3. The minimum value that be specified in the STARTING AT LINE clause
is 2. Note that prompts specified with the PMT (for prompt) keyword
always appear on line 2. The PMT keyword is explained later in this
chapter.
4. If you don't specify a STARTING AT LINE clause, or Line and Position
fields, the starting position for the first field will be the first position in line
3. Each field that follows will be in the next available display position
following the previous field.
The defaults for line and position entries ensure that the Status Line and the
prompt line at the top of the screen aren't overlayed, whether STARTING
AT LINE is specified or not. The following table shows the relationship
between STARTING AT LINE values, line entries in columns 39-41, and the
physical line on the screen where the field will appear.
STARTING Value Cols. 39-41 Screen Line
Blank (default 3) Blank
Next available position
Blank (default 3)
3
Blank (default 3) 2 4
Blank (default 3) 3
5
3
Blank Next available position
3 1 3
3 2
4
3
3 5
4 Blank Next available position
4 1 4
4 2
5
4 3 6
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