NOTE this text may need refinement but represents the gist of the matter
Geoff Mayo used to be employed by a firm called TRE, before forming Cajon Rail LLC. TRE supply SimSig-like sims to the railway industry and have privileged access to industry sources to do that. Network Rail supplies their data under a Non-Disclosure Agreement (NDA) and if Geoff turns it into a SimSig for public release he's responsible for the breaking of that agreement and liable to be an Unpopular Person. So he cannot legitimately work on a new simulation of any area that TRE produces a simulation of, which at present is basically all the IECCs. (other workstation-controlled computer-operated systems may also be on the banned list.)
SimSig in fact predates TRESim and it's understood that Geoff got his present job as a result of an early SimSig being used by the big railway to train some of its signallers. So there are a couple of "old" IECC SimSigs that Geoff wrote using data he'd sourced himself; being demonstrably not a result of data supplied under the NDA these remain available. Geoff no longer works on them though, as the boundary would become just a little too thin.
It might be possible for Geoff to permit simulation of IECC areas by other developers, but only in very limited circumstances, and clarity of the non-conflict of interest is paramount, insofar that it can be clearly shown that he was not the source of the data. That is a significant concession, but it does mean that anyone concerned with building an IECC sim has to be doubly careful; it is vital that nothing be done that might compromise Geoff's professional position and he will not have any dealings at all with such a sim while it's being written.
In addition, TRE make their money by selling things that can't be bought elsewhere. TRE therefore would prefer Geoff to not publish sims of areas that TRE produce as it might well affect their market (I doubt Network Rail would pay TRE for their training sims if they knew where they could get them for free). So Geoff is limited by that as well.
If a simulation is an IECC, that is the conflict of interest. There are legal sanctions that can be deployed if Geoff doesn't observe these restrictions. Geoff very sensibly takes the view that, although there is the potential to work right up to the boundaries, he wishes to keep a clear margin so there can be no possibility of problems arising.
There are occasions, such as Marylebone IECC, where a simulation is produced that is on the "not allowed" list. These are usually because there is a paper trail to the supplier.
Please respect these restrictions, including any decision Geoff takes to not work too close to the boundaries - or to produce a simulation previously on the "not allowed" list.
Last edited by GeoffM on 15/09/2016 at 03:00