The trader may need to trade the asset (due to some trading ideas or investment restrictions), which is quoted not like in common currency pair, but in another currency at the trader’s discretion. The trader may get just a new cross rate, but the method can be applied for non-currency assets, as well. For example, trading Gold, quoted against the Australian Dollar -there is no such instrument in the common market – in this case the trader creates «@XAU/AUD» synthetic instrument, gets all charts on it for full analysis and a trading opportunity.
This class can also include the opportunity to quote a currency (or even an asset) against a subset of common instruments, used by the trader. For example, a trader, due to his investment preferences, wants to analyze and trade the Singapore Dollar, Brent Oil, Gold and Caterpillar Inc. stocks, quoting all these instruments against the Australian Dollar (thereby choosing AUD as the funding currency). In that case, it will be enough to create four PCIs (it takes several minutes) - “@SGD/AUD”, “@#C-BRENT/AUD”, “@XAU/AUD, “@#S-Cat/AUD”.