How does sodipodi:linespacing determine the vertical spacing to the next line?

From a bit of experimenting it looks like it starts with this:

sodipodi:linespacing="125%"

and then looks at the maximum font size in all of the <tspan>'s included under the following

<tspan sodipodi:role="line"

and multiplies those together. So if the largest is 16pt, it uses 20pt for the linespacing.

Is there anything else involved, or is that the entire method?

Also, if this is all inside a <text> with

style="font-size:32.000000pt;font-style:normal;font-variant:normal;font-weight:400;font-stretch:Normal;line-height:125%;letter-spacing:0px;word-spacing:0px;fill:#000000;fill-opacity:1;stroke:none;text-align:start;text-anchor:start;font-family:Arial;"

Changing font-size or line-height makes absolutely no difference in the display. Is that how it should be?

Thanks,

David Mathog mathog@...1176... Manager, Sequence Analysis Facility, Biology Division, Caltech