The bug in Tally 9 Release 2.1 relating to XML tags in proper-case issue has been rectified in Tally 9 Release 2.12.
In March 2008, we had noticed it and had put it up at this blog-site. For those who are not aware of it, can read it here.
Now, in Tally 9 Release 2.12 when we export Masters or Vouchers, the XML tags that are generated are in UPPER-CASE and this is in line with Older versions of Tally except for Tally 9 Release 2.1 wherein the XML tags were generated in Proper-case.