To make the MVG applet read-only, you could use the "Parent BC Read Only" user property.

You have two business components with parent - child relationship as following.

Parent BC: Opportunity Product
Child BC: AB Oppty Supplementary Card Details

1. You should create the calculated field to be changed depending on the field value of one of parent business component.
For example, in Opportunity Product,
Name: RO Flag
Calculated Value: IIf([Type]= "Administration", "Y", "N")

- [Type] is a field name in parent business component to be check if it has any specific value.
- You should set "Link Specification" property to TRUE.

2. You should add the user property to the child business component
For example: in AB Oppty Supplementary Card Details,
Name: Parent Read Only Field
Value: Action.Opportunity Product

3. Compile and execute the application.