I found the following at the Puppylinux website:

Q: May I release my own distro based on Puppy?
A:
Yes, but you need to obtain permission from me, which is a precaution to prevent anything weird happening.

One basic rule is that you must choose a name for your distro that provides sufficient "product differentiation" from "Puppy", "Puppy Linux" and "PuppyOS".

(Later....)

Another rule is that your project site must fully acknowledge myself, Barry Kauler, as the original developer and current maintainer of Puppy and there must be a link to my website, www.puppyos.com (or www.puppylinux.com)

(Still later.....)

Distribution is allowed, "hacking" is allowed, however Barry Kauler must always be acknowledged and the website www.puppylinux.com included in the acknowledgement. Spawning of parallel or divergent projects must be with the agreement of Barry Kauler.
I cannot find anything like this on the Knopper website or the licence. So my question is whether the same legalities as for Puppylinux apply to Knoppix:

1) Spawning of parallel and divergent projects (for example, customised remasters) must be with the agreement of the original developer?

2) Project website must acknowledge the original developer?

3) Name must be sufficiently different? But I see there is clusterknoppix, parallelknoppix and so on. In Puppylinux, Clusterpuppy is not allowed but Clusterpup would be.

I know all the above are courteous things to do, but I want to be clear about precise legal obligations.

Any advice would be appreciated.