The Enter key
Pressing the Enterkey performs two different functions depending on the settings in the Tools > Options > OpenOffice.org Calc > Generaldialog. The Enterkey can be programmed to:
When both options are selected, pressing the Enter key switches to Edit mode and the cursor moves to the Input line.Pressing the Enterkey again commits the data from the Input line to the currently selected cell and moves the selection to a cell in the direction specified in the Optionsdialog.
To insert a manual line break within a cell, click in the cell (make sure the cursor is in the cell and is blinking), and then press Control+Enter.