Complex sentence: The first truss piece, the Z1 truss, launched aboard STS-92 in October 2000 was used as a temporary mounting position for the P6 truss and solar array until its relocation to the end of the P5 truss during STS-120.
Split into simpler sentences: The first truss piece, the Z1 truss, launched aboard STS-92 in October 2000. Another objective of the Z1 truss was to serve as a temporary mounting position for the "P6 truss and solar array" until its relocation to the end of the P5 truss during STS-120.