请教PB6.0代码的含义
											long i
long j
long ll
string ls_xkzh
ls_xkzh = trim(parent.sle_1.text)
for i = 1 to 16
    if i < 5 then
        j = i * 3
    end if
    if j > 15 then
        j = j - 5
    end if
    ls_xkzh = replace(ls_xkzh,i,1,char(asc(mid(ls_xkzh,i,1)) - j - 16))
next
ll = long(left(ls_xkzh,10))
if right(ls_xkzh,6) <> right(string(ll / 23 - gl_mc),6) or mod(ll,gl_mc) <> 0 or len(ls_xkzh) <> 16 or isnull(ls_xkzh) then
    messagebox("","错误!")
    parent.ii_serial_times ++
    if parent.ii_serial_times > 3 then
        halt
    end if
    return
end if



											
	    

	