Editing considerations in your application

Before you describe the editing requirements of your application, be sure that you are aware of your standards concerning screen design. Make sure that the requirements that you describe comply with those standards.

Provide the following information about your program's editing requirements:

• How you want the screen to be presented to the person at the terminal for the person to enter the input data. For example, if an airline agent wants to reserve seats on a particular flight, the screen that asks for this information might look like this:

  FLIGHT#:
  NAME:
  NO. IN PARTY:

• What the data should look like when the person at the terminal enters the input message.
• What the input message should look like in the program's I/O area.
• What the data should look like when the program builds the output message in its I/O area.
• How the output message should be formatted at the terminal.
• The length and type of data that your program and the terminal will be exchanging.

The type of data you are processing is only one consideration when you analyze how you want the data presented at the terminal. In addition, you should weigh the needs of the person at the terminal (the human factors aspects in your application) against the effect of the screen design on the efficiency of the application program (the performance factors in the application program). Unfortunately, sometimes a trade-off between human factors and performance factors exists. A screen design that is easily understood and used by the person at the terminal may not be the design that gives the application program its best performance. Your first concern should be that you are following whatever are your established screen standards.

A terminal screen that has been designed with human factors in mind is one that puts the person at the terminal first; it is one that makes it as easy as possible for that person to interact with IMS. Some of the things you can do to make it easy for the person at the terminal to understand and respond to your application program are:

• Display a small amount of data at one time.
• Use a format that is clear and uncluttered.
• Provide clear and simple instructions.
• Display one idea at a time.
• Require short responses from the person at the terminal.
• Provide some means for help and ease of correction for the person at the terminal.

At the same time, you do not want the way in which a screen is designed to have a negative effect on the application program's response time, or on the system's performance. When you design a screen with performance first in mind, you want to reduce the processing that IMS must do with each message. To do this, the person at the terminal should be able to send a lot of data to the application program in one screen so that IMS does not have to process additional messages. And the program should not require two screens to give the person at the terminal information that it could give on one screen.

When describing how the program should receive the data from the terminal, you need to consider the program logic and the type of data you are working with.