Tables & Classes involved in Sales Order

SalesTableType and SaleslineType classes will get called while creating the SalesOrders.
SalesFormLetter_Confirm
SalesFormLetter_Invoice
SalesFormLetter_PackingSlip
SalesFormLetter_PickingLlst
classes will be used to post the sales order at various document status (packing, invoice etc).
Tables:
SalesTable contains all SalesOrder headers regardless whether they have been posted or not.
The SalesParmTable and SalesParmLine contains detailed information regarding posting sales headers and Lines.
CustConfirmJour and CustConfirmTrans tables contains all Sales Confirmation headers and Lines posted in Dynamic Ax originating from Sales Orders and Lines.
CustPackingSlipJour and CustPackingSlipTrans tables contains all sales PackingSlip headers and Lines posted in Dynamic Ax originating from Sales Orders and Lines.
CustInvoiceJour and CustInvoiceTrans tables contains all sales all Sales Invoice headers and Lines posted in Dynamic Ax originating from Sales Orders and Lines.