How to avoid output of ItemTypes definition of collection in XML

Hi,

my next simple question is belong the following XML-section:
<Hyperbolaes>
<Hyperbola xmlns="" i:type="Hyperbola">
<A2>23104</A2>
<ApexX>120</ApexX>
<ApexY>152</ApexY>
<B2>692.37677001953125</B2>
</Hyperbola>
</Hyperbolaes>

can a avoid the otput of ' xmlns="" i:type="Hyperbola" ' if I
serialize collection of objects known types? I think, the output of
i:type makes no sense, because the type is the same, as XML-
Elementtype and known by program.

Many thanks!