text dx/dy

The following example gives different results in Adobe SVG viewer and Batik

 <text x="40" y="51px">
  This<tspan dy="5 5 5 5 5" style="font-size:16;">is</tspan>Test
 </text>

Adobe SVG Viewer applies the first two dy values to the 'is' and then
applies the remaining 3 dy values to 'Tes'

My question is: which is correct?

thanks,

--
Sigurd Lerstad