ACCA P3考试：INFORMATION TECHNOLOGY

　　Example: Royal Bank of Scotland

　　A software update was applied on 19 June 2012 to RBS's system which controls its payment processing. The update had been corrupted by RBS technical staff so that customers' wages, payments and other transactions were disrupted. Many customers were unable to withdraw cash using automatic teller machines and were not able to see their bank account details. Others faced fines and surcharges for late payment of bills because the system could not process direct debits. For many customers the disruption lasted for around a week.

　　APPLICATION CONTROLS

　　Application controls are manual or automated procedures that typically operate at a business process level, such as the processing of sales orders, wages and payments to suppliers.

　　These controls help ensure that transactions are authorised, and are completely and accurately recorded, processed and reported. Examples include:

　　Edit checks of input data

　　Checks on input data are very important because once data has been input it is often automatically processed thereafter without the further chance of human scrutiny. Methods include:

　　• Range tests can be applied to reject data outside an allowed range. For example, when accepting orders through a website, the system could be programmed to prevent, or at least query, unusually large quantities being ordered.

　　• Format checks ensure that data is input in the correct format (credit card numbers should be 12 digits long).

　　• Dependency checks, where one piece of data implies something about another (you have probably had a travel booking rejected because you inadvertently had a return date earlier than the outward date).

　　• Check digits, where a number, such as an account number, is specially constructed to comply with mathematical rules. For example, UK and European VAT numbers use this method:

　　VAT number = GB 2457193 48 (the last two digits, here 48, are the check digits)

　　The first seven numbers are multiplied by the weighting factors 8, 7, 6, 5, 4, 3, 2:

　　So 2 x 8 + 4 x 7 + 5 x 6 + 7 x 5 + 1 x 4 + 9 x 3 + 3 x 2 = 146

　　Subtract 97 until the result is zero or negative:

　　146 – 97 – 97 = -48

　　The resulting number is the check digit. The chances of someone incorrectly typing in a VAT number which accidentally followed these rules are very small.

　　• Numerical sequence checks to ensure that all accountable documents, such as cheques, have been processed.

　　• Drop down menus which constrain choices and ensure only allowable entries can be made. For example, constraining delivery choices to ordinary post or express delivery, or presenting a list of allowable account codes.

　　• Batch total checks. Here, the data is first added up to create a control total, which is subsequently compared to the total of the data actually submitted.