I am not able to provide the CDT as "Type" in SAIL Interface. It has o

make the input an 'Any Type', and then when testing the form use a type constructor for the initial value (e.g. =type!yourCDT())

If you are trying to pass a CDT into an interface as a rule input, then you can pass it with the Any Type option. If this is not what you are trying to do, it might be helpful to provide additional context or screenshots.

I am trying pass CDT as Interface input and save the fields into CDT.

Should I use like this ? "saveInto:type!VFM_VEHICLES(ri!VFMVehicle.VEHICLE_NAME)"

My CDT name is : "VFM_VEHICLES", Interface input name is "VFMVehicle" with type as "Any Type"

With this I got below error,
"Interface Definition: Expression evaluation error at function a!util_sasaUiSource: An error occurred while executing a save: Expression evaluation error : The save target must be a load() variable, process variable, or node input (or a rule input passed one of those three), but instead was: [VEHICLE_NAME=, VEHICLE_CATEGORY=, VEHICLE_DESC=, VEHICLE_ID=, NO_OF_SEATS=, YEAR=, LAST_MAINTENANCE=, SATISFACTION_RATING=, STATUS=, MAKE=]"

I am not getting any error if I use "saveInto:type!VFM_VEHICLES(ri!VFMVehicle).VEHICLE_NAME". Let me test and get back..

Leave the saveInto as ri!VFMVehicle.VEHICLE_NAME

When you test the form, you can put an initial value into the rule inputs. That is where you'll use the type constructor because Appian needs to know what type the 'Any Type' is.

This works for test form. But when I execute the form from Tasks I get same error. I have below in Form tab of my Task,

=rule!VFM_addVehicleForm(VFMVehicle:ac!VFMVehicle))

This is difficult without seeing your application, but make sure the ac!VFMVehicle is mapped correctly in the data tab, and then map that into the process variables.. Also make sure your interface is saved