What kind of transaction type for the "HL Road Frame - Black, 48" order happened in 2012/12/13?
Transactiontype = 'w' means 'WorkOrder'; transactiontype = 's' means 'SalesOrder'; transactiontype = 'P' means 'PurchaseOrder'; happened in refers to TransactionDate
SELECT T1.TransactionType FROM TransactionHistory AS T1 INNER JOIN Product AS T2 ON T1.ProductID = T2.ProductID WHERE T2.Name = 'HL Road Frame - Black, 48' AND STRFTIME('%Y-%m-%d',T1.TransactionDate) = '2013-07-31'