No. Organizations such as ASTM and IEC only publish minimum specifications for selected magnetic properties such Br and Hci, since these are usually the only specifications that a magnet supplier will guarantee.
The reality is the BH curve of any magnet material (not just N50) will vary from batch to batch, so determining a 'reference' BH curve isn't practical. Guaranteeing minimum magnetic properties is much more feasible and accepted in the industry.
When I design a magnet circuit, I design to minimum specifications of Br and Hci. Except for unusual applications, this is sufficient.
Since this is the 2nd time you asked this type of question, it must be important to you. If that is the case, I suggest you take all the N50 curves from the various suppliers you have contacted and average them together. This will approximate a reference curve for your own applications.
