||Offset.rb is intended for developers to use with their plugins.
It may be used as-is, via an "include" statement, with a simple acknowledgement in the code comments:
include "offset.rb" # version 2.201 (c) Rick Wilson, used by permission. http://www.smustard.com/script/Offset
A small acknowledgement on your web page with a link to our main page would be appreciated, but is not required.