Offset of origin (defaults to 0), which shifts the lower and upper bound by a fixed amount, namely the offset.
Setting the offset to
x means lower and upper bounds have
x added to them.
This option is shared by all parametric distributions, but perhaps is not very useful for the uniform distribution, since the same effect can be obtained by changing the values of lower and upper bound by a fixed amount. So, for a uniform distribution, leaving it at zero would be perfectly fine.
Jordan Douglas’ distribution viewer: