The account code represents the account which data will be pulled from. Without identifying the account, nothing can be returned.
The Account Code is typically expressed as a combination of three letters and a 4 digit number. It is case sensitive and the letters are always lower case. An example: abc1234
When creating API calls, specify the account code by using the customer parameter: https://omi.zonarsystems.net/interface.php?customer=abc1234.