Why do you need copy-back?

[Sanjoy Mahajan]

> Only in the case that the product is deployed and _not_ distributed,
> for example in the ASP model, would this term become important. Take
> a look at the (admittedly clunky) way that this is addressed in the
> "Affero GPL".

I think it is stated cleanly in the Open Software License (v2.1):

  5) External Deployment. The term "External Deployment" means the use
  or distribution of the Original Work or Derivative Works in any way
  such that the Original Work or Derivative Works may be used by anyone
  other than You, whether the Original Work or Derivative Works are
  distributed to those persons or made available as an application
  intended for use over a computer network. As an express condition for
  the grants of license hereunder, You agree that any External
  Deployment by You of a Derivative Work shall be deemed a distribution
  and shall be licensed to all under the terms of this License, as
  prescribed in section 1(c) herein.

The provision comes from a similar one in the Real Networks Public
Source License (p.195 of Larry Rosen's _Open Source Licensing_).

-Sanjoy