horizontal white lines in edit view

[Willie Toth]

Waveform View (the default) displays a waveform as a series of positive and negative peaks. The x-axis (horizontal ruler) represents time, and the y-axis (vertical ruler) measures spikes, or increased amplitude, in a waveform.”

[Blast1]

[diederik] “What is the meaning of this lines ?”

They are called Boundary Lines, they are controled in the Preferences Menu-> Display Tab, avaiable in the Edit Menu Dropdown, you can turn them on/off and adjust the level they appear at, -1DB is the default, you can set them to use as a guide for circumstants where you don’t want to exceed a certain level, like the safe areas for video, -1DB is a good point for clipping