Every software I have seen, contain copyright statement at the beginning of a file and takes pretty much lines of comment. Therefore you have to scroll down to see the code, which is a bit annoying, especially when code itself is very short.
I think that it would be nicer to keep copyright statement at the bottom of a file and join all clauses into single (or few) lines. This would be just to satisfy formal issues. Easy to read version is available in LICENSE file.
But I haven’t seen such practice so far. Is it just a tribal custom or is there a reason for that?
edit: Here’s <list> from GNU STL library as an example:
// <list> -*- C++ -*-
// Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING. If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.
// As a special exception, you may use this file as part of a free software
// library without restriction. Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License. This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.
/*
*
* Copyright (c) 1994
* Hewlett-Packard Company
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Hewlett-Packard Company makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
*
* Copyright (c) 1996,1997
* Silicon Graphics Computer Systems, Inc.
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Silicon Graphics makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*/
/** @file list
* This is a Standard C++ Library header. You should @c #include this header
* in your programs, rather than any of the "st[dl]_*.h" implementation files.
*/
#ifndef _GLIBCXX_LIST
#define _GLIBCXX_LIST 1
#pragma GCC system_header
#include <bits/functexcept.h>
#include <bits/stl_algobase.h>
#include <bits/allocator.h>
#include <bits/stl_construct.h>
#include <bits/stl_uninitialized.h>
#include <bits/stl_list.h>
#ifndef _GLIBCXX_EXPORT_TEMPLATE
# include <bits/list.tcc>
#endif
#ifdef _GLIBCXX_DEBUG
# include <debug/list>
#endif
#endif /* _GLIBCXX_LIST */
While it’s not necessarily a custom or requirement, standards tend to dictate that comments should proceed any code definition. Take a look at NDOC notation as an example.
In the case of a copyright you generally want people to read it before they proceed with using your code (EULAs are always displayed at the beginning of an installer). If a copyright notice is placed at the bottom of the code definition there’s a good chance it will be overlooked.