Animation of tspan dx and dy
dx and dy attributes change with animations for blue texts
without explicitly given absolute text positions x and y, therefore
the current text position is computed automatically without any
absolute text positions given by x and y.
The same effect is gained using animations for x and y of grey stroked texts below.
Therefore the blue texts cover approximately the grey stroked texts. Differences in the
y direction indicates an error as well as major differences in x, minor differences in x
are ok and may depend on the used font for monospace.
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