// level may borrow at any one time.
  // This field holds the ratio of that limit to the level's nominal
  // concurrency limit. When this field is non-nil, it must hold a
  // non-negative integer and the limit is calculated as follows.
  //
  // BorrowingCL(i) = round( NominalCL(i) * borrowingLimitPercent(i)/100.0 )
  //
  // The value of this field can be more than 100, implying that this