Input/output fields (I/O fields) are fields in the work area of a window. Here the user can enter information, or the system displays already known data in them.
Input fields are used for entering data. They may be set to read-only status. This is useful, for instance, when a task can be toggled between display and change mode. Another useful situation is when the user navigates to a subsequent screen. There the user can view the data entered on the previous screen but cannot change them.
Pure output fields display information. In the R/3 System, they are used as field names, as table or column headings, and to show descriptive texts (see figure 1).
Depending on their function, I/O fields look differently:
You set the corresponding flags in the Screen Painter.
Read-only and output fields can be chosen with the active control indicator (Windows: Ctrl arrow key) and with the mouse. This allows the user to request help and to position the active control indicator in a selection table.
Figure 1: A typical R/3 screen with different types of fields and with group boxes
Further characteristics of I/O fields:
Input/output fields are usually assigned to a field name and positioned to the right of it. A descriptive text may follow to the right of the I/O field. Fields can be clustered into blocks. These can be further assembled into block groups consisting of one or more blocks. A typical block group consists of a block of field names and a block of corresponding input fields.
Separate field name and I/O field by at least two blanks. Separate the descriptive text from the I/O field by at least three blanks to leave room for the possible entries pushbutton (Exception: tables).
Displaying Output Values
Exception: The leading zero for the month should be displayed.
Net value 12.323.411,23 Date 12.12.90
Positioning Quantity and Currency Units
Place quantity or currency units to the right of the value. Leave only one blank between value and quantity or currency unit (see example 1).
Exception: If units are usually positioned to the left of the value, follow this arrangement in order to not confuse the user.
Check if you can include the unit in the field name (see example 2). In this case the quantity unit should appear in parenthesis. Insert a blank between field name and quantity unit and make sure that there are at least two blanks at the end of the entire field name.
I/O Fields With Several Parts
You can assign several I/O fields to a field name if (1) you split an I/O field into several logical parts or (2) several related I/O fields are together on the screen.
Try to split the field name in accordance with the I/O fields. Separate the individual parts of the I/O field from one another by meaningful special characters. Place the special characters as close to the I/O fields as possible. Remember, however, that some special characters might have a different meaning in other countries.
Plant/storage location _____ / ______
Number of I/O Fields per Field Name
Exception: The following fields have no field names:
Scrollable Input/Output Fields
I/O fields can be made scrollable. Scrollable I/O fields use less space on the screen, because they display fewer characters than they are actually long. That is, their "visible" length is shorter than their "physical" length. Use scrollable I/O fields where space requirements are tight. There is, however, one disadvantage: Users see only one part of the information, they have to scroll to see the rest.
You can recognize scrollable input fields by their dotted borders to the left and to the right. Scrollable output fields show only dots at the right border.
Figure 2: Scrollable output field
Scrollable descriptive texts are displayed flat on the screen. A right pointing arrow at the end of the text signifies that the text is scrollable.
Figure 3: Scrollable descriptive text
Source: SAP R/3 Style Guide