Sign

1 when the value is above zero, -1 when below, 0 at exactly zero: direction without size.

Sign keeps only the direction of its input. On the default close it is 1 on every bar, since prices are positive. On a price change it marks up-bars with 1 and down-bars with -1, and an unchanged bar with 0.

How to read it

The line sits in its own pane and only takes the values -1, 0 and 1.
On the default close it is a flat line at 1.
On a change or an oscillator, runs at 1 or -1 show a streak in one direction.

What it outputs

Sign: 1 above zero, -1 below zero, 0 at zero.

Pitfalls

On prices it is a flat line at 1; feed it a change, such as the close minus the previous close, to see direction.