The measurement quoted in dB describes the ratio (10 log power difference, 20 log voltage difference, etc.) between the quantity of two levels, the level being measured and a reference.
Alt Codes for Bracketing ; Alt Code Symbol Description Alt 40 ( Open Bracket Alt 41 ) Close Bracked Alt Codes for Degree of Accuracy ; Alt Code Symbol Description Alt 241 Â± Plus or Minus Alt Codes for Fractions ; Alt Code Symbol Description Alt 47 / Fraction seperator
A QWERTY keyboard layout with the position of Control, Alt and Delete keys highlighted. Control-Alt-Delete (often abbreviated to Ctrl+Alt+Del, also known as the three-finger salute) is a computer keyboard command on IBM PC compatible computers, invoked by pressing the Delete key while holding the Control and Alt keys: ++.