Thanks for the question. "No arbitrary nesting" applies to inline formatting. Higher precedence formatting can be nested within lower. So, nothing can be neste

Thanks for the question. "No arbitrary nesting" applies to inline formatting. Higher precedence formatting can be nested within lower. So, nothing can be nested within a code span, for example, as it is the highest. Just a way to order things. Container blocks are nested arbitrarily, up to 16 levels. Quote > list > quote > code, for example, is OK.