trigger are created when master -detail relay

Which trigger are created when master -detail relay?

master delete property
* NON-ISOLATED (default)
a) on check delete master
b) on clear details
c) on populate details
* ISOLATED
a) on clear details
b) on populate details
* CASCADE
a) per-delete
b) on clear details
c) on populate details

which system variables can be set by users? 
SYSTEM.MESSAGE_LEVEL
SYSTEM.DATE_THRESHOLD
SYSTEM.EFFECTIVE_DATE
SYSTEM.SUPPRESS_WORKING

What are object group? 
An object group is a container for a group of objects. You define an object group when you want to package related objects so you can copy or reference them in another module.

What are referenced objects? 
Referencing allows you to create objects that inherit their functionality and appearance from other objects. Referencing an object is similar to copying an object, except that the resulting reference object maintains a link to its source object. A reference object automatically inherits any changes that have been made to the source object when you open or regenerate the module that contains the reference object.

Can you store objects in library? 
Referencing allows you to create objects that inherit their functionality and appearance from other objects. Referencing an object is similar to copying an object, except that the resulting reference object maintains a link to its source object. A reference object automatically inherits any changes that have been made to the source object when you open or regenerate the module that contains the reference object.

Is forms 4.5 object oriented tool ? why? 
yes , partially. 1) PROPERTY CLASS - inheritance property 2) OVERLOADING : procedures and functions.