Based on the provided legal document, the key points regarding the procedure for age determination inquiry under the Juvenile Justice (Care and Protection of Children) Act, 2000, and Rules, are as follows:

1. The procedure for age determination must be found within the enactment that confers jurisdiction to hold such inquiry, specifically the Juvenile Justice Act and Rules (!) .

2. The inquiry is distinct from investigation or trial and is limited to establishing the age of the juvenile or child in conflict with law (!) (!) .

3. The court or the Juvenile Justice Board (JJB) or Committee is obliged to conduct an 'age determination inquiry' within thirty days of the application, seeking evidence based on available documents and, if necessary, medical opinion from a duly constituted Medical Board (!) (!) .

4. The evidence that can be relied upon includes:

5. Matriculation or equivalent certificates, if available;
6. The date of birth certificate from the school first attended;

7. The birth certificate issued by a municipal or panchayat authority (!) (!) .

8. If these documents are unavailable or found to be fabricated or manipulated, the court or the Board may seek a medical opinion, which is only conclusive if it indicates the age is below 18 years and must be recorded accordingly (!) (!) .

9. In cases where the exact age cannot be conclusively determined, the benefit of juvenility should be given by considering the child's age on the lower side within a margin of one year (!) .

10. The order passed after such inquiry shall be the conclusive proof of age for the purpose of determining juvenility, and no further inquiry shall be conducted after this order unless additional circumstances warrant (!) (!) .

11. The inquiry is a procedural step under the Juvenile Justice Act and Rules, and it is critical that courts follow the specific procedures laid out therein, avoiding procedures under the Criminal Procedure Code (Cr.P.C.) meant for investigations, inquiries, or trials (!) (!) (!) .

12. The court or authority should act as a parens patriae, acting in guardianship to protect minors, and should seek evidence such as certificates or documents rather than conducting a detailed investigation or trial into the authenticity of the documents, except in cases of suspected fabrication (!) (!) .

13. The procedure emphasizes the importance of relying on authentic, official documents and certificates, and medical evidence should only be sought when such documents are unavailable or suspected to be manipulated (!) (!) .

In summary, the age determination inquiry under the Juvenile Justice Act and Rules is a specialized, evidence-based process that must be conducted within a strict procedural framework, focusing on documented evidence and medical opinion only when necessary, to ensure an accurate and fair determination of juvenility.