# Defining Conversion Rules

You can define a new conversion rule definition or select an existing conversion rule definition for modification.

## Prerequisites

Ensure that you have done the following tasks:

- Defining Messages
- Defining Buffers

## Procedure

1. Select option 3 - Define Conversion Relationships to go to the Conversion Rules panel.
   For more information about this panel, see Conversion Rules Panel.
2. Type either of the following commands:
   - To create a new entry, enter `ADD` on the command line, and then press Enter.
   - To select an existing definition to modify, enter `S` in the Sel field, and then press Enter.
3. In the Sel field, enter `S` next to the message definition you want to use, and then press Enter.
   For more information about this panel, see Select a Message Definition Panel.
4. In the Sel field, enter `S` next to the buffer definition you want to use, and then press Enter.
   For more information about this panel, see Select a Buffer Definition Panel.
5. In the Conversion ID field, enter up to 16 characters to name the conversion rule definition.
6. In the Max Buffer Size field, enter (if applicable) a value to use for the maximum buffer size.
7. In the Trunc field, enter `Y` or `N` to truncate data that extends beyond the specified buffer length.
8. In the Reqd field, enter `Y` or `N` to indicate if the field is required.
9. In the BfFld field, enter the sequence number of the buffer field that maps to the message field for the transformation.
10. Press Enter before exiting the panel.
11. Exit the Define Conversion Rules panels in either of the following ways:
    - Press PFK3.
    - On the command line, enter `END`, and then press Enter.
12. Review the message displayed in the upper-right corner of the Transformer Configuration panel to verify that your changes have been saved and that no error messages are displayed.

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