Difference between restricted and unrestricted package procedure

Restricted package procedure that affects the basic functions of SQL * Forms. It cannot used in all triggers except key triggers. Unrestricted package procedure that does not interfere with the basic functions of SQL * Forms it can be used in any triggers.

Difference between OPEN_FORM and CALL_FORM

When one form invokes another form by executing open_form the first form remains displayed,
and operators can navigate between the forms as desired.
when one form invokes another form by executing call_form,
the called form is modal with respect to the calling form.
That is, any windows that belong to the calling form are disabled,
and operators cannot navigate to them until they first exit the called form.

Eg:

When we invoke a form from OPEN_FORM built-in, we can freely move to calling form and called form.
When we invoke a form from CALL_FORM built-in, we cannot move to the calling form unless we complete our work in the called form and close it.

We have FormA, FormB.
We open the formB from FormA.
OPEN_FOR('FormB');
We can move the focus to FormA and FormB without closing FormB.

CALL_FORM('FormB');
In this case, when FormB os opened, we have to complete the required work in FormB and have to close FrmB before moving the focus to FormA.

We cannot move the focus to FormA unless we close FormB