Is a Curve Timelike, Spacelike, or Null?

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If I have a line element ds^{2} = ... and a curve defined by x^{1} = f( \lambda ), x^{2} = g( \lambda ) etc, and I wand to know if the curve is timelike, spacelike, or null, do I do so by checking the sign of g_{\mu \nu} \frac{dx^{\mu}}{d\lambda} \frac{dx^{\nu}}{d\lambda} ?
 
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