due to the limited size, the short describtions are not perfect. however, PTCT and NTCT are "Positve Temperature Coefficient Thermistors" and "Negative Temperature Coefficient Thermistors", so they are actually no real n- or p-doped silicons.

here a "short" overview of their combinations and functions:

1. if a spark goes from METL to NTCT or PTCT, it will heat up NTCT's and PTCT's to 200°C.

2. a spark will only go from PSCN to NTCT, if the temperature of the NTCT is over 100°C.
3. a spark will only go from PSCN to PTCT, if the temperature of the NTCT is under 100°C.
4. a spark will always go from NSCN to NTCT and PTCT.

5. a spark will always go from NTCT/PTCT to PSCN.
6. a spark will always go from PTCT to NSCN.
7. a spark will only go from NTCT to NSCN, if the temperature of the NTCT is over 100°C.
(note that 6. and 7. are odd! the functions should be more consistent. 6. should work like this:
a spark will only go from PTCT to NSCN, if the temperature of the PTCT is under 100°C.)

8. a spark will never go form NTCT/PTCT to METL.
9. a spark will never go from PTCT to NTCT, vice versa.

that's it. have fun to use the new metalls.