rendered paste body <body>
<par dur="indefinite">
<par id="A_par" begin="bt_A.activateEvent" end="bt_B.activateEvent">
......
</par>
<par id="B_par" begin="bt_B.activateEvent" end="bt_A.activateEvent">
<par id="B_par_text1" begin="0s;arrow_b.activateEvent" end="B_par.end;arrow_f.activateEvent">
<textstream id="B_text1" src="..." rn:backgroundOpacity="0%" transIn="fade_1" region="text_B_a" end="B_par_text1.end;bt_A.activateEvent" fill="freeze"/>
<textstream id="B_text2" src="..." rn:backgroundOpacity="0%" transIn="fade_1" region="text_B_b" end="B_par_text1.end;B_par.end" fill="freeze"/>
</par>
<par id="B_par_text2" begin="arrow_f.activateEvent" end="B_par.end;arrow_b.activateEvent">
.......
</par>
</par>
</par>
</body>
</smil>