Sets the starting contour level value. Must be less than `contours.end`

If `levels`, the data is represented as a contour plot with multiple levels displayed. If `constraint`, the data is represented as constraints with the invalid region shaded as specified by the `operation` and `value` parameters.

Sets the value or values of the constraint boundary. When `operation` is set to one of the comparison values (=,<,>=,>,<=) *value* is expected to be a number. When `operation` is set to one of the interval values ([],(),[),(],][,)(,](,)[) *value* is expected to be an array of two numbers where the first is the lower bound and the second is the upper bound.

Sets the fill color if `contours.type` is *constraint*. Defaults to a half-transparent variant of the line color, marker color, or marker line color, whichever is available.

Determines whether or not gaps (i.e. {nan} or missing values) in the `z` data have hover labels associated with them.

Sets the color of the contour level. Has no effect if `contours.coloring` is set to *lines*.

Sets the amount of smoothing for the contour lines, where *0* corresponds to no smoothing.

Sets the contour line width in (in px) Defaults to *0.5* when `contours.type` is *levels*. Defaults to *2* when `contour.type` is *constraint*.

Sets the maximum number of contour levels. The actual number of contours will be chosen automatically to be less than or equal to the value of `ncontours`. Has an effect only if `autocontour` is *true* or if `contours.size` is missing.

Sets the text elements associated with each z value.

For this trace it only has an effect if `coloring` is set to *heatmap*. Sets the text font.

For this trace it only has an effect if `coloring` is set to *heatmap*. Template string used for rendering the information text that appear on points. Note that this will override `textinfo`. Variables are inserted using %{variable}, for example "y: %{y}". Numbers are formatted using d3-format's syntax %{variable:d3-format}, for example "Price: %{y:$.2f}". https://github.com/d3/d3-format/tree/v1.4.5#d3-format for details on the formatting syntax. Dates are formatted using d3-time-format's syntax %{variable|d3-time-format}, for example "Day: %{2019-01-01|%A}". https://github.com/d3/d3-time-format/tree/v2.2.3#locale_format for details on the date formatting syntax. Every attributes that can be specified per-point (the ones that are `arrayOk: true`) are available. variables `x`, `y`, `z` and `text`.