An apparatus and method of encoding eye movements and eye tracking data, represented as time and space parameters obtained by an eye tracking device and assigned each to a viewpoint. A carrier forming a part of the planetary gear reduction mechanism is mounted in a non-rotating state on an open end side of the spindle. The transition seal structure includes a transition base portion that defines a first axially facing surface, a first transition lip member extending axially from the first axially facing surface, and a second transition lip member radially spaced from the first transition lip member and extending axially from the first axially facing surface. The software-layer commands are compatible with each logical node. Textual directions are generated for traversing a path associated with the positional data, based in part on link information associated with the links of the generated routing graph.