sqlldr 参数配置

into table sqlldr
( 
SubsId position(1:15) "Trim(:SubsId)", 
Name position(16:45) "Trim(:Name)",
Sex position(46:47) "decode(:Sex,'F','0','1')",
status position(48:49) "Trim(:status)",
score position(50:55) ":score/100"
)

问下各位，那个position（48：49）有什么作用？？谢谢