What information should be included in a request for a private letter ruling?

In what circumstances will the IRS rue on estate tax issues?

On which of the following issues will the IRS likely issue a private letter ruling and why? In your answer, assume that no other IRS pronouncement addresses the issue and that pertinent Treasury Regulations are not forthcoming: [a] Whether the taxpayer correctly calculated a capital gain reported on last years tax return; [b] The tax consequences of using stock derivatives in a corporate reorganization; [c] Whether a mathematical formula correctly calculates the fair market value of a stock derivative