The ry attribute defines a radius on the y-axis.

The JavaScript exception "invalid regexp group" occurs when the sequence (? does not start a valid group syntax. Recognized group syntaxes that start with (? include:

The viewBox attribute defines the position and dimension, in user space, of an SVG viewport.

The pointsAtZ attribute represents the z location in the coordinate system established by attribute primitiveUnits on the <filter> element of the point at which the light source is pointing, assuming that, in the initial local coordinate system, the positive z-axis comes out towards the person viewing the content and assuming that one unit along the z-axis equals one unit in x and y.

The startOffset attribute defines an offset from the start of the path for the initial current text position along the path after converting the path to the <textPath> element's coordinate system.

The style attribute allows to style an element using CSS declarations. It functions identically to the style attribute in HTML.

The JavaScript exception "malformed URI sequence" occurs when URI encoding or decoding wasn't successful.

The JavaScript exception "cyclic object value" occurs when object references were found in JSON. JSON.stringify() doesn't try to solve them and fails accordingly.

A lookbehind assertion "looks behind": it attempts to match the previous input with the given pattern, but it does not consume any of the input — if the match is successful, the current position in the input stays the same. It matches each atom in its pattern in the reverse order.

The JavaScript exception "illegal character" occurs when the lexer reads a character that's not part of a string literal, and the character cannot constitute a valid token in the language.