The g1 attribute specifies a list of glyph names which identify a set of possible first glyphs in the kerning pair.

A named capturing group is a particular kind of capturing group that allows to give a name to the group. The group's matching result can later be identified by this name instead of by its index in the pattern.

The subtraction assignment (-=) operator performs subtraction on the two operands and assigns the result to the left operand.

The data-* SVG attributes are called custom data attributes. They let SVG markup and its resulting DOM share information that standard attributes can't, usually for scripting purposes. Their custom data are available via the SVGElement interface of the element the attributes belong to, with the SVGElement.dataset property.

The yield operator is used to pause and resume a generator function.

The for statement creates a loop that consists of three optional expressions, enclosed in parentheses and separated by semicolons, followed by a statement (usually a block statement) to be executed in the loop.

The edgeMode attribute determines how to extend the input image as necessary with color values so that the matrix operations can be applied when the kernel is positioned at or near the edge of the input image.

The flood-opacity attribute indicates the opacity value to use across the current filter primitive subregion.

The assignment (=) operator is used to assign a value to a variable or property. The assignment expression itself has a value, which is the assigned value. This allows multiple assignments to be chained in order to assign a single value to multiple variables.

The for...in statement iterates over all enumerable string properties of an object (ignoring properties keyed by symbols), including inherited enumerable properties.