The logical level at the start of the maneuver. For maneuvers that go up or down levels, such as going from floor 1 to floor 2 in a building's stairwell, the from-level value signifies the start level of the maneuver. For example, to go from floor 1 to floor 2, the from-level would be 1 and the to-level would be 2. If these values are in the source data, the directions engine can give a descriptive instruction for the maneuver, such as "go up the stairs." If the values are not provided, a -1 value is used, signifying that no levels are defined for maneuvers.