PluginSchedulingMode  - преобразование (PluginSchedulingMode to String)

public static explicit operator string (
	PluginSchedulingMode schedulingMode
)

Public Shared Narrowing Operator CType ( 
	schedulingMode As PluginSchedulingMode
) As String

static explicit operator String^ (
	PluginSchedulingMode^ schedulingMode
)

F# не поддерживает объявление новых операторов приведения.