What do you mean by the word (payload)?
On PASC sub-accounts are called payloads. If you go to Poloniex and get a deposit address for Pascal coin you use their account number and a payload they assign to your account. Any deposits to this account and payload get credited to your PASC balance on Poloniex, for example. Payloads per account are unlimited.
That is not actually correct. Using payment transaction payload field for "sub account" addressing is not a feature of PascalCoin. That is the workaround implemented by Poloniex to be able to serve and account users transaction to the one poloniex's account.
Payload is just an operation comment (which could be encrypted though). All you can do with PascalCoin Wallet is to browse the payload. You can not use it as sub account number (neither filter transactions nor get the balance for "sub account" or spend funds from it).