Strange numbers in "Create your own urdf file" URDF's tutorial

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Hello! I recently started studying ROS and now I'm considering this tutorial

I don't understand how the axis xyz values (from Completing the Kinematics) was calculated. The follow values are given at first:

  <axis xyz="0 1 0" />

for joint2 and

<axis xyz="-0.707 0.707 0" />

for joint1.

But after that in the general .XML file are given:

 <axis xyz="-0.707 0.707 0" />

for joint2 and

<axis xyz="-0.9 0.15 0" />

for joint1.

As i know vectors for axis xyz should be normalized, but "-0.9 0.15 0" is not normalized. What are the correct values? Thanks.

I use Ubuntu 16.04 and ROS kinetic.