An exact instruction block suppresses code optimizations
    (SCHEDULE and PEEPHOLE) regardless if these optimizations are
    enabled for the assembly unit. Unlike .ENABLE and .DISABLE, which
    can be used to enable or disable specific optimizations for the
    entire assembly unit, .BEGIN_EXACT and .END_EXACT allow you to
    suppress optimization for a specified range of instructions.
    Instructions outside the specified range remain subject to any
    optimizations you have enabled.