Ok JD,
I'll rephrase it so you understand what I was meaning, although my premise is correct.
TL is
one step in the calculation (note the bold) that is used to work out the MSFL etc.
To quote my qoute, that you quoted(!!)
-
The TL is used primarily to ensure a minimum separation requirement exists between the TA and the Minimum (Useable) Flight Level.
The TL
may be less than 500' - hence the reference you quoted (with your bold).
What I was getting at when I typed that sentence was that to see if separation does actually exist between the TA and the T Level, you need to work out the T Layer. Hence, the T Layer is primarily (within the calculation) to ensure a minimum separation... etc etc. It doesn't really serve any other function.
If it separation doesn't naturally exist (highlighted when the T Layer is calculated) because the QNH does not differ dramatically enough from the SAS, then the MSFL is moved up accordingly.
