diff --git a/docs/02-Scales.md b/docs/02-Scales.md
index 79549c43d..5597b4c1a 100644
--- a/docs/02-Scales.md
+++ b/docs/02-Scales.md
@@ -19,6 +19,7 @@ Name | Type | Default | Description
 type | String | Chart specific. | Type of scale being employed. Custom scales can be created and registered with a string key. Options: ["category"](#scales-category-scale), ["linear"](#scales-linear-scale), ["logarithmic"](#scales-logarithmic-scale), ["time"](#scales-time-scale), ["radialLinear"](#scales-radial-linear-scale)
 display | Boolean | true | If true, show the scale including gridlines, ticks, and labels. Overrides *gridLines.display*, *scaleLabel.display*, and *ticks.display*.
 position | String | "left" | Position of the scale. Possible values are 'top', 'left', 'bottom' and 'right'.
+id | String | | The ID is used to link datasets and scale axes together. The properties `datasets.xAxisID` or `datasets.yAxisID` have to match the scale properties `scales.xAxes.id` or `scales.yAxes.id`. This is especially needed if multi-axes charts are used.
 beforeUpdate | Function | undefined | Callback called before the update process starts. Passed a single argument, the scale instance.
 beforeSetDimensions | Function | undefined | Callback that runs before dimensions are set. Passed a single argument, the scale instance.
 afterSetDimensions | Function | undefined | Callback that runs after dimensions are set. Passed a single argument, the scale instance.