The JavaScript exception "invalid class set operation in regular expression" occurs when a double punctuator sequence appears in a v-mode character class but it is not recognized by the syntax.

The primitiveUnits attribute specifies the coordinate system for the various length values within the filter primitives and for the attributes that define the filter primitive subregion.

The JavaScript exceptions thrown by JSON.parse() occur when string failed to be parsed as JSON.

The JavaScript exception "import declarations may only appear at top level of a module" occurs when an import declaration is not at the top level of a module. This might be because the import declaration is nested in other constructs (functions, blocks, etc.), or more often because the current file is not treated as a module.

The panose-1 attribute indicates the Panose-1 number of a font face.

The specularExponent attribute controls the focus for the light source. The bigger the value the brighter the light.

The requiredFeatures attribute takes a list of feature strings, with the individual strings separated by white space. It determines whether or not all of the named features are supported by the browser; if all of them are supported, the attribute evaluates to true end the element is rendered; otherwise, the attribute evaluates to false and the current element and its children are skipped and thus will not be rendered. This provides a way to design SVG that gracefully falls back when features aren't available.

The JavaScript exception "missing ) after argument list" occurs when there is an error with how a function is called. This might be a typo, a missing operator, or an unescaped string.

The pointsAtY attribute represents the y location in the coordinate system established by attribute primitiveUnits on the <filter> element of the point at which the light source is pointing.

The JavaScript exception "missing ) after condition" occurs when there is an error with how an if condition is written. It must appear in parenthesis after the if keyword.