While this could be a specific technical identifier (like a motherboard model or firmware version), it's most likely one of the following:
Could you clarify if you are looking for a for a specific piece of hardware, or if you are looking for scientific research on Retinoic Acid Receptors? BP95N rar
You might be looking for information on how to handle or extract a "solid" .RAR archive (a method where multiple files are treated as one block to increase compression). While this could be a specific technical identifier
Reexpression of retinoic acid receptor (RAR) gamma or ... - PMC BP95N rar