Overview of Model 204 commands

This page describes the syntax of all Model 204 control commands. The commands page provides an alphabetical listing of links to the command descriptions.

In general, all the information necessary to issue and use a command is included in the command description.

Cross-referencing other Model 204 documentation

Many commands are best understood in the context of more global concepts introduced in other Model 204 manuals. For example, the description of the checkpoint commands, CHECKPOINT, CHKABORT, and CHKMSG, can be supplemented by the general description of checkpoint and restart facilities in the Rocket Model 204 System Manager’s Guide. The field description and field attributes mentioned in the presentation of fields for the DEFINE and REDEFINE commands are described in greater detail on those pages.

Commands are context sensitive

If not otherwise indicated, you can issue a command from within a procedure. However, some of the system control commands cannot be issued from within a procedure. If procedure specification is not permitted for an individual command, this is indicated in the command description.

You can issue most commands in either file or group context (that is, when the current default is either a file or a group). In some cases, as indicated in the descriptions of the commands, commands can be issued only in file context.

What Model 204 commands do

System control commands instruct Model 204 to perform specified operations. Unlike User Language statements, which you must compile in Model 204 before you can run them, commands are executed immediately.

Commands as system interface

Commands provide the first system interface between users and Model 204. For example, at most installations, a user must issue a LOGIN command to establish communication Model 204.

To enter and run a User Language request, first you must open a Model 204 file with the OPEN command and enter a BEGIN or MORE command. To invoke any of the Editor functions, you must enter an EDIT command. Commands also create files and groups, define procedures, and perform a wide variety of other functions.

Typical command operations

There are approximately one hundred Model 204 commands. The following list summarizes some representative operations that you can perform with these commands:

• Logging in and out of Model 204
• Creating files or groups
• Defining or redefining the fields in a file
• Opening and closing Model 204 files and groups
• Defining procedures
• Displaying file, group, record, and field information, procedure text, and access rights
• Deleting groups, procedures, and fields
• Protecting files and procedures from unauthorized access
• Examining and resetting Model 204 parameters
• Sending a message to the operator or to another user
• Requesting system monitoring functions

Using the asterisk (*) character in User Language

The asterisk character is used the following ways in User Language:

• As a pattern matcher in the ordered index.
  For example,

  FIND FIELD IS LIKE ABC*

• In column one (or the first position in a line of code) to begin a comment.
  For example,

  *

• At the beginning of non-published commands, such as *CANCEL, *LOOK, or *ZAP.
  Non-published commands are not documented for Model 204 because they are not intended for regular customer use, but you might at times be advised to use them by Rocket Software Technical Support.

Command level and user type

Using Model 204 commands requires understanding of the two basic concepts introduced in this section: command level and user type. Model 204 commands can be classified by the type of user that is allowed to issue them. This section differentiates the user types and lists the individual commands that each user type can issue. Command level System control commands are issued only from command level. You are at command level when Model 204 is waiting for input other than the following:

• Editor command after an EDIT command has been issued
• Response to a Model 204 prompt (for example, after a $READ prompt)

The text of a procedure can include system commands. Commands entered within a procedure are part of the procedure. They are not run until the procedure itself is run as a result of an INCLUDE or IF command.