Choosing a short name for a namespace can eventually lead to a name clash. On the other hand, very long namespaces are not easy to use. For that purpose, namespace aliases can be used:
//file decl.hnamespace Excel_Software_Company { class Date {/*..*/};class Time {/*..*/};//...other declarations }//file calendar.cpp#include "decl.h"void main(){namespace ESC = Excel_Software_Company; //ESC is an alias for Excel_Software_CompanyESC::Date date;ESC::Time time;//...rest of the program}