Each terminal has several keys that are available to be used for special purposes. Some of these keys are used as field termination keys, others are used as editing keys. ACUCOBOL-GT supports a large number of special keys, but in the default configuration, only these are used:
| Function Keys 1-20
| Help
|
| Arrow Keys
| Do
|
| Page Up
| Page Down
|
| Backspace
| Line-Kill
|
| Home
| End
|
| Insert
| Delete
|
| Clear
| Clear to End
|
| Carriage Return
| Control Keys |
The keyboard interface can be easily configured to meet a variety of needs. The default configuration has the following characteristics:
1. The range of legal input characters is ASCII values 32 through 255. Other characters outside this range are ignored unless covered by one of the cases below.
2. The range of exception characters is ASCII values 1 through 31. If any of these characters is typed, an exception condition exists and input to the field is terminated. The exception key value is identical to the ASCII value of the key. For example, if Control-E is typed, then the exception key value returned would be "5". This rule does not apply to characters specifically listed in rule 3.
3. The following table outlines the actions of other keys. In this table, Action is the special action performed by the key. If a number is present here, then this key terminates the field and returns that number as its termination key value. If the number is starred (*), then this key also causes an exception condition. If there are both a number and an action, then the key acts as a termination key when the action cannot be applied.
The Windows/MS-DOS column names the keycap on the IBM-PC keyboard that is used for this key. The Termcap column names the terminal database file entry that corresponds to this key for UNIX and VMS systems.
| Key
| Action
| Windows/MS DOS
| Termcap
|
| Carriage Return
| 13
| Enter
|
|
| Tab
| Next Field (9)
| Tab
|
|
| Host's Backspace
| Backspace
| BkSp
|
|
| Host's Line-Kill
| Erase Field
|
|
|
| Backtab
| Previous Field
| Shft-Tab
| kB
|
| Home
| First Field
| Home
| kh
|
| End
| Last Field
| End
| KE
|
| Insert
| Auto-Insert Mode
| Ins
| KI
|
| Delete
| Delete Character
| Del
| KX
|
| Clear
| Erase Field
| Ctl-Home
| KC
|
| Clear-to-End
| Erase Remainder
| Ctl-End
| kE
|
| Left Arrow
| Left
| Left
| kl
|
| Right Arrow
| Right
| Right
| kr
|
| Up Arrow
| Previous-All (52*)
| Up
| ku
|
| Down Arrow
| Next-All (53*)
| Down
| kd
|
| Page Up
| Page-Up (67*)
| PgUp
| kP
|
| Page Down
| Page-Down (68*)
| PgDn
| kN
|
| Do (Command)
| 40*
| Alt-D
| KD
|
| Help
| 90*
| Alt-H
| K?
|
| F1 - F10
| 1 - 10*
| F1 - F10
| k1 - k0
|
| F11 - F20
| 11 - 20*
| Shft F1 - F10
| K1 - K0
|
There are four different methods for accepting a field (ACCEPT verb, Format 1), depending on the mode and the presence of either the CONTROL KEY clause or the ON EXCEPTION clause. These are:
Standard mode, no CONTROL KEY or ON EXCEPTION clause: the field can be accepted only by a termination key. In the default keyboard configuration, these are the Carriage Return and Tab keys.
Standard mode, with CONTROL KEY or ON EXCEPTION clause: the field can be accepted by a termination key or by one of the exception keys.
Auto mode, no CONTROL KEY or ON EXCEPTION clause: the field can be accepted by a termination key or by filling the field with data.
Auto mode, CONTROL KEY or ON EXCEPTION clause: the field can be accepted by filling it with data, or by a termination key or an exception key.
The Terminal Manager can control more than one field when the program is doing an ACCEPT that refers to a Screen Section item (ACCEPT verb, Format 2). In the course of this ACCEPT, the user can move between the fields by using the Tab, Backtab, Left, Right, Up, Down, Home and End keys; the Tab key acts as a terminate key only in the last field. A Format 2 ACCEPT statement does not support the use of the CONTROL KEY clause; the CRT STATUS phrase of the Special-Names paragraph may be substituted. Data entry for a Screen otherwise falls into four categories much like the above.
The termination and exception keys may be changed by runtime configuration options as described in section 4.3.2, "Redefining the Keyboard."
2. ACUCOBOL-GT defines more editing keys than RM/COBOL-85 does. In particular, the Home, End, Clear, Clear-to-End and Line-Kill keys return exception values under RM/COBOL-85, while under ACUCOBOL-GT they perform various field-editing functions.
3. ACUCOBOL-GT defines Page Up, Page Down, and Help keys that are not defined under RM/COBOL-85. These keys are used by the ACUCOBOL-GT debugger.
4. The default RM/COBOL-85 keyboard includes the following keys as exception keys: Attention, Home, New Line, Tab Left, Erase Right, Tab Right, Insert Line, Delete Line, and Send. Under ACUCOBOL-GT, these keys either act as editing keys or are ignored. Because these keys are generally not available on most keyboards (or, in the case of the Tab Right and New Line keys, are ambiguous with control keys), most applications do not use them. If you need to use any of these keys, you can alter the ACUCOBOL-GT keyboard configuration as described in section 4.3.2, "Redefining the Keyboard."
5. The RM/COBOL-85 default keyboard layout varies from machine to machine. In the interest of portability, the default ACUCOBOL-GT keyboard interface is the same for all machines.