Update CHANGELOG

Author: mbostock

CHANGELOG.md

@@ -4,7 +4,7 @@
 
 *Not yet released.* These notes are a work in progress.
 
-The new *plot*.**scale**(*name*) method exposes scales used by a particular plot. This method on returned plots takes the *name* of a scale and returns an object containing scale options that fully describe the scale’s behavior. The returned object represents the actual options in-use, including *scale*.domain, *scale*.range, *scale*.interpolate, *etc.* The *scale*.label, if any, is also returned; however, note that other axis options are not. The scale object is undefined if the associated plot has no scale with the given *name*, and throws an error if the *name* is invalid (*i.e.*, not one of the known scale names: *x*, *y*, *fx*, *fy*, *r*, *color*, or *opacity*). For example, given a plot:
+The new *plot*.**scale**(*name*) method exposes scales used by a particular plot. This method on returned plots takes the *name* of a scale and returns an object specifying the options that fully describe the scale’s behavior. The returned object represents the actual options in-use, including *scale*.domain, *scale*.range, *scale*.interpolate, *etc.* The *scale*.label, if any, is also returned; however, note that other axis options are not. The scale object is undefined if the associated plot has no scale with the given *name*, and throws an error if the *name* is invalid (*i.e.*, not one of the known scale names: *x*, *y*, *fx*, *fy*, *r*, *color*, or *opacity*). For example, given a plot:
 
 ```js
 myplot = Plot.dot(gistemp, {x: "Date", y: "Anomaly", stroke: "Anomaly"}).plot()
@@ -34,6 +34,8 @@ Inspecting materialized scales is useful for debugging and for generating color
 Plot.plot({…, color: myplot.scale("color")})
 ```
 
+The new *scale*.**unknown** option provides more control over how unexpected or undefined values are displayed. For quantitative and temporal scales, the unknown value is used whenever the input value is undefined, null, or NaN. For ordinal or categorical scales, the unknown value is returned for any input value outside the domain. For band or point scales, the unknown option has no effect; it is effectively always equal to undefined. If the unknown option is set to undefined (the default), or null or NaN, then the affected input values will be considered undefined and filtered from the output.
+
 Plot now supports piecewise (a.k.a. “polylinear”) scales. If a single-argument *interpolate* function is specified (such as d3.interpolateWarm, or equivalently if you specify a color *scheme* such as *warm*), and the *range* is undefined, and the *domain* has more than two elements, the range [0, 1] will be partitioned into *domain*.length - 1 same-sized segments. The default scale range for *x* and *y* now supports piecewise scales, as does the default axis tick count.
 
 Plot now automatically detects “reversed” quantitative or temporal scales with descending domains or ranges. Reversed scales are detected by comparing the natural order of the domain and range. This improves the default axis label arrow orientation and the behavior of the *zero* option.
@@ -46,8 +48,12 @@ The *interval* option for rect and bar now works with the default identity acces
 Plot.barX(d3.utcDays(start, end), {interval: d3.utcDay, fill: d => d})
 ```
 
+Plot’s default rounding behavior for band and point scales is now slightly smarter. Previously, automatic rounding could introduce substantial empty space on tall or wide plots; now Plot disables default rounding if it would introduce more than 30px of empty space.
+
 The *percent* and *transform* options are now supported on all scales, including diverging scales.
 
+The *center* and *wiggle* stack offsets now center across facets, facilitating comparison.
+
 Internal string coercion now uses *object*.toString instead of *object*.valueOf.
 
 ## 0.2.4