Sort income and expenses report by absolute value of account, largest to smallest.

[Peter Ross]

I would like to sort my income and expenses report by absolute value
of account, largest to smallest.

I believe the following command line is correct

ledger --sort -UT bal income expenses

and I get the following output

$ ledger --sort -UT bal income expenses
While evaluating value expression:
  UT
  ^^
Error: Unknown identifier 'UT'

$ ledger --sort -T bal income expenses

works as expected.

Is this a bug or a misunderstanding on my part?