I think there may be a bug in the <lookat> element documentation. The text for the example gives an eye position of (10,20,30), while the XML example below it shows a matrix with eye position 2.0 0.0 3.0. This makes it unclear whether the matrix was calculated in some other manner not stated in the spec, or whether it is in fact a typo.
See 1.4 spec, page 5-75 and 5-76.
See 1.5 spec, page 5-86 and 5-87.