  We have performed V-I measurements on a thin film YBa2Cu3O7 4^o [001] tilt
low angle grain boundary over an extensive range of temperature and field,
verifying the presence of a linear characteristic. We report on the occurrence
of the linear characteristic in its basic form and on the observation of V-I
kinking into several, and in some cases numerous, linear segments. We interpret
these findings in terms of a variation in the dissipative width at the grain
boundary. Kinking from one linear V-I section to another of different gradient
is described in terms of a change in the number of vortex rows being viscously
channeled along the boundary.
