account Assets:Cash
account Expenses:Phone
account Expenses:Rent
commodity GBP
tag bar

2012-03-20 * Phone
    ; :bar:
    Expenses:Phone            20.00 GBP
    Assets:Cash

2012-03-21 * Rent
    Expenses:Rent            550.00 GBP
    Assets:Cash

2012-03-22 * Food
    ; :food:
    Expenses:Food             20.00 EUR
    Assets:Cash

test bal --explicit --strict
          -20.00 EUR
         -570.00 GBP  Assets:Cash
           20.00 EUR
          570.00 GBP  Expenses
           20.00 EUR    Food
           20.00 GBP    Phone
          550.00 GBP    Rent
--------------------
                   0
__ERROR__
Warning: "$FILE", line 18: Unknown account 'Expenses:Food'
Warning: "$FILE", line 18: Unknown commodity 'EUR'
Warning: "$FILE", line 19: Unknown metadata tag 'food'
end test