Indeed, libudfread is not rocket science.
However Wikipedia says:
"For example, a UDF 2.01 volume that does not use Stream Files (introduced in UDF 2.00) but uses VAT (UDF 1.50) created by a UDF 2.60-capable implementation may have the revision declared as 0x0201, the minimum read revision set to 0x0150, the minimum write to 0x0150, and the maximum write to 0x0260."