Question: What is a barcode whitelist?
Answer: A barcode whitelist is the list of all known barcode sequences that have been included in the assay kit and are available during library preparation.
For example, there are roughly 737,000 cell barcodes in the whitelist for Cell Ranger's Single Cell 3' and V(D)J applications. Here are the first 10 lines of the corresponding barcode whitelist 737K-august-2016.txt:
You can find the barcode whitelist file bundled inside your Cell Ranger installation, e.g.