I'd say in an ideal world they'd be separate blocks but to save on detection I've made mine part of the block to which the toe of the turnout connects. I worked on the basis you couldn't enter that block from either of the diverging routes if it was occupied so you couldn't run onto the turnout. In the other direction you could exit the block via the turnout to one of the two diverging routes if the other was occupied. Does that make sense?
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Chris White
Christopher White