UpdateCount keeps track of whether all update operations have been completed. When an application starts making changes to the list, it calls BeginUpdate, which increments UpdateCount. When those changes are complete, it calls EndUpdate, which decrements UpdateCount. Thus, UpdateCount allows calls to BeginUpdate and EndUpdate to be nested. 

Applications can avoid responding to updates in a piecemeal fashion by checking UpdateCount and only responding when it is 0. For example, the callback that is supplied to the TXMLNodeList constructor typically checks UpdateCount before responding to change notifications. 

BeginUpdate 

EndUpdate 

Create