GLCode from this list cannot be removed from the system
1) inventory
2) inventoryCost
3) generalSales
4) generalSalesReturn
5) accReceivable
6) accPayable
7) retainedEarnings
8) profitLoss
9) cashDiscount
10) purchases
11) purchaseReturns
12) generalSalesDiscount
13) gstPayable
14) badDebt
15) interestRevenue
16) interestBankCharges
17) creditCardCharges
18) inventoryVariance
19) forexGainLoss
20) crvExpense
Source : /wavelet/src/com/vlee/bean/accounting/MergeGLCodeForm.java