Access the FASB Accounting Standards Codification at the FASB website (www.fasb.org). Determine the specific eight-digit Codification citation (XXX-XX-XX-X) that describes each of the following items: 

1. The basic principle for recording nonmonetary transactions at fair value. 

2. Modifications of the basic principle for recording nonmonetary transactions when fair value is not determinable or the exchange lacks commercial substance. 

3. The concept of commercial substance. 

4. The required disclosures for nonmonetary transactions.