Why does Bitstamp allow trading of currencies that it won't return a balance for? According to https://www.bitstamp.net/api/ section "Buy Limit Order" Bitstamp allows users to buy LTC coins using the currency pair "ltcusd". But, looking at the "Account Balance" section, there is no way to get a user's LTC balance.

What happens when a user buys "ltcusd"? Where does the LTC balance go?
Contrary to the documentation, the server actually returns a balance for LTC, BCH and ETH coins using fields ltc_available, bch_available and eth_available, respectively.