You can access the Service Plan Custom Fields setting in the Control Panel to add and manage Custom fields to store additional information about service plans.

To access the Service Plan Custom Fields setting, click the following icon.

This will open the following form.

SI has 24 Custom fields for service plans.

To add a new custom field for service plans:

1/ Click New.

2/ Select the type of field.

Over time, you will see how many fields are already in use and how many are available.

3/ Add a name for the field.

4/ To reorder the fields, use the Move Up button and the Move Down button.

5/ Click Save.

When adding a List type field, you can click Manage in the List section in the menu and add the options that should be displayed in the dropdown.

You can use the Move Up button and the Move Down button to order the options and set the case of the text in the options.

The custom fields added for service plans are shown under the Custom Fields tab in the New Service Plan form. You can add the values for the fields when adding the plan or editing its details.

Check out this article for more details.