Animation of tspan dx and dy with tref inside
dx and dy of tspan ('abcdefgh') containing a tref ('cdef') with values
for the dx and dy attributes explicitly set for 'cd'
is animated with a values animation.
The visible result is that the blue 'abgh' and 'cdef'
cover exactly the red ones.
If something red gets visible, this indicates an error.
cdef
a
b
c
d
e
f
g
h
abgh