id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
18	Why are there often internal and external include guards?	dneise	somebody	"Often one finds external include guards like:
{{{
#ifndef MARS_MInputStreamID
#include ""MInputStreamID.h""
#endif
}}}

While the file being included already has an internal guard

{{{
------ contents of MInputStreamID.h -------
#ifndef MARS_MInputStreamID
#define MARS_MInputStreamID

/* Definition of class MInputStreamID */

#endif
}}}

Is this needed by the ROOT CInt, or is it just a historical left over?"	enhancement	new	trivial		component1