Components in Visual LANSA are defined using a BEGIN_COM/END_COM pairing. Be they a Form, Reusable Part or other component type all code for the component is within this BEGIN_COM/END_COM pairing. For Field Visualization what we have done is exposed the component side of a field for end user modification. What this means is that you can open a Field in the component editor and modify its code as you would any other Visual LANSA component.
This does not mean that you can start creating events and using all Visual LANSA commands within the component aspects of a field (as most commands are illegal and will flag as an error) But it does mean that certain aspect of the Visual LANSA language have been exposed to help end user modification of the component aspects of a field.
To explain further the reason that all LANSA commands are not available from the Field Component source is that the Field source is never executed. All code entered is used to only construct the component form of the Field. Therefore all LANSA commands that are execution related will flag an error in the Editor.