markee174: If Castle were to grant me code under the BSD license (I presume the DSD was a typo) I would still be able to do what I wished with it without paying them a fee. Read the license here, [link] Dual licensing allows people to choose which of the two licenses to be bound by, it would not allow Castle to say, use this one when I tell you, or this other one when I tell you. The other 57 licenses listed here [link] would also not allow Castle to charge a license fee.
What is suggested above in the article is a commercial software model which uses public contributions, in which the code is viewable but contributors have no guaranteed rights to it, it is not an open source model. Microsoft has released the source code to several programs under terms similar to this.
If Castle want to Open Source RISC OS, they should. If they want to keep it commercial, they should. But by confusing the two whilst making up 'Yet another license' will confuse and limit contributions, the 'Open Source' community  is very vocal and will have no issues vilifying Castle if Castle were to claim their commercial license was 'Open Source'. Whereas that very community is the one you wish to engage if you want to leverage their huge skills base .
 The FSF, OSI, OSDN, Sourceforge, Slashdot etc etc etc.
 I know of several former RISC OS programmers that currently work on Open Source projects that could be temtped back in to the fold if RISC OS were to be open sourced.