Document Structure

From Svg wiki

Where is document structure covered in the SVG specification?

Document structure is covered in section 5 of the SVG specification.

Is the <g> element redundant in SVG, given the fact that it has similarity to the <svg> element?

No. Jon Ferraiolo writes:

The <g> has at least one attribute that an <svg> doesn't have -- the 'transform' attribute, and the <svg> has many attributes that a <g> doesn't have, particularly document-level attributes. There are many notes in the SVG spec about unique behavior with <svg> elements. While they overlap quite a bit, there are clear differences...