A simple cdata element, contained inside a text element. The attributes from the text element are provided through the open argument list.
dx, dy originate from sibling elements! Here the args element inside the parent object must be altered, too.
fixme (Roger) 07/13/2009 :a tspan element might not have any dx or dy values, which makes it necessary to calculate the text width (and height) and apply it accordingly. dy only appears for newlines, and then the x or dx values are being set. Requires: text and font extraction, then call »font measure for it« to get the position, and dimension. –font measure is way to buggy in Tk to get any substantial result for this type of operation. Can’t be done properly!
The above »fixme« is very important for »sub« and »super« elements, which depend on proper coordinates...
sub is aligned with the lower outer line while super is aligned with the higher outer line together with its own »ascent«–superscript does not exceed the linespace, subscript however may.