private 命令示例

*** 演示 private 的程序示例***
set talk off
val1 = 10
val2 = 15
do down
? val1, val2  && 显示 10, 100
procedure down
private val1
val1 = 50
val2 = 100
? '       val1       val2'
? val1, val2  && 显示 50, 100
return