Creating partition may serve different purposes. The common reason is that a separate partition can be used to store data files so that when Windows needs to be reinstalled, the main partition can be formatted without fear of loosing data, which are stored on the other partition.
RDO is Hierarchy model where as ADO is Object model. ADO can access data from both flat files as well as the data bases. I.e., It is encapsulation of DAO, RDO , OLE that is why we call it as OLE-DB Technology.
User defined functions can be created into the Microsoft spreadsheet. Spreadsheets can be customized according to the user needs by using VB applications. To create visual basic functions useful for spreadsheet you need to click Tools and select Macros where you will need to click on Visual basic editor.