Fields and Formatted Displays
The various areas
of
bank checks
that
always contain the same type
of
informa-
tion are called "fields" in data-processing language, for example, the
"date"
field
or the "signature" field. Most documents
to
be entered into a host system will
be organized by fields.
This practice
of
standardizing the arrangement
of
data originated because the
person using the information could do his or her job much faster knowing that
one type
of
data would appear at the same location on every document.
When a display station screen
is
divided into fields, it makes working with the
display station quicker and easier for
both
the display station operator and the
host system program. The application program divides the screen into fields and
establishes the rules
as
to what each field will contain. The program then knows
that the same type
of
information will always be displayed in the same location.
Knowing this, the program can process the data from the screen much more
quickly. The operator can also perform his or her job more efficiently having
this information.
When a screen
is
divided into fields, it
is
known
as
a formatted screen. A screen
that the program has not divided into fields
is
known
as
an unformatted screen.
Eachjob that you work on could use a different format or none at all; therefore,
you may be working with
both
fonnatted and unformatted screens.
Input
Fields
You may
see
two types
of
fields on your screen. One
is
primarily used by the
program
to
send you messages, instructions, and headings; you cannot key data
into this type
of
field.
All
of
your entries will be into the other type. For this
reason, in the remainder
of
this manual, fields
that
you can key data into will be
referred
to
as
input fields. Each application program user's guide should tell you
which are the input fields for
that
particular job.
Once a field
is
assigned
to
one type
of
data in a job, those character positions
should not be used for other data items in that job. For example, one field
on
the screen in Figure
2-3
is
called "STOCK NO". That
is
the only type
of
infor-
mation you will key into it.
You will not, for instance, key the digits
of
an MFG
CODE number into the STOCK
NO
field. (Otherwise, the display station key-
board may stop functioning or a message may appear on the screen telling you
of
the error.)
There
is
no rule stating
that
fields must always be a certain length or that there
will always be the same number
of
fields
on
the screen. The length
of
a field
is
normally arrived at
by
determining, from the type
of
information
that
will be
entered in the field, the longest possible length
of
one entry. In many cases, this
is
known. For example,
all
Stock numbers could be the same length, 9 digits;
therefore, the field for Stock numbers
is
9 character spaces long. When the max-
imum length
is
not known,
as
in a field marked for customer name, maximum
length must be estimated by some method, and the field length must be set
from that estimate.
The number and names
of
fields that you will
see
on your screen will depend
on
the job you are doing and the application program
that
is
operating in the
host system.
Chapter 2 Controls and Indicators 2-13
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