mmm, have I understood you correctly?
1..You have a select box, EG:
2..If AAA,111 is selected you want to place them in a textarea?
if (document.fromName.selectBoxName.value == "AAA,111")
document.fromName.textAreaName.value = "AAA,111"
else if (document.fromName.seectBoxName.value == "someOtherValue")
document.fromName.textAreaName.value = "someOtherValue"
Then in your select tag fire the function onChange:
<select name="selectBoxName" onChange="moveText();">
Wind is your friend