Need more explain 'bout sharktooth x264 video profile

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<EncodingMode>4</EncodingMode> --> what it's mean
<Turbo>true</Turbo> --> ???
<V4MV>false</V4MV> --> ???

thx for all

[check]

<EncodingMode>4</EncodingMode>The index of the selected mode in the "mode" dropdown. The index starts at 0.
<Turbo>true</Turbo>Assuming a compatible mode is chosen, use a faster first pass.
<V4MV>false</V4MV>Some xvid setting.