* change lower case to upper case in "firm id"
local i = 1998
  while `i' <= 2006{
use m`i'.dta, clear
replace id`i'=upper(id`i')
save m`i'.10.dta, replace
local i = `i' + 1
  }

local i = 1998
  while `i' < 2006{
  local j=`i'+1

**step 10: match by firm ID**

工企数据匹配中，Brandt代码中的local i = `i' + 1是什么意思，是错了吗求解答，多谢！还有replace id`i'=upper(id`i')这个命令是什么意思呢？