[1] The fair-value method uses either the price on a market or calculates the value using a mathematical formula such as the Black–Scholes model, which requires various assumptions as inputs.
[4] Stock options under International Financial Reporting Standards are addressed by IFRS 2 Share-based Payments.
A single SAR is a right to be paid the amount by which the market price of one share of stock increases after a period of time.
The preference for fair value appears to be motivated by its voluntary adoption by several major listed businesses, and the need for a common standard of accounting.
Opposition to the adoption of expensing has provoked some challenges towards the unusual, independent status of the FASB as a non-governmental regulatory body, notably a motion put to the US Senate to strike down "statement 123".