* --U- means the transaction has committed, so any row data referencing the ITL is not involved in an active transaction and is therefore not locked. The transaction's row data may not be consolidated. By consolidated I mean, for example, if a column was updated, both the before and after values can remain in the row data.

* C--- means the transaction has been committed, row data has been consolidated, and the ITL entry in the row data has been removed. Any block touch can (but does not always) trigger the change to this flag value, including a select statement. I realize this is difficult to believe, so I will demonstrate it shortly. This seemingly delayed change is commonly referred to as a delayed block cleanout, or simply a block cleanout.

* Lck: This is the number of rows the transaction has, at some point, locked in this block. A value greater than 0 does not indicate a row(s) is currently locked. If the number is 2, as is the case with the second transaction shown in Figure 6-37, the transaction is related to two rows. The lock value remains until the flag changes to a C---. This means after a transaction has committed and is no longer deemed active (flag of --U-), the Lck value can be greater than zero.