According to the ECB DLP "...contain ex post data (in EUR millions) on volumes of: 1) open market operations; 2) recourse to the marginal lending facility; 3) use of the deposit facility; 4) autonomous liquidity factors; 5) current account holdings; and 6) reserve requirements".
Daily Percent Change in ECB Daily Liquidity Conditions
According to the ECB BA "...is the allotment amount in the main refinancing operations that allows counterparties to smoothly fulfil their reserve requirements, taking into account the expected liquidity supply through other open market operations and the ECB's forecast of autonomous factors and excess reserves".
Overnight deposits at the ECB. More on TARGET2 and its terms and conditions here.