dcm4che and dcm4chee are licensed under an MPL/GPL/LGPL triple license - similar to Mozilla. This allows use of the files under the terms of any one of the Mozilla Public License version 1.1 (MPL), the GNU General Public License version 2 or later (GPL), or the GNU Lesser General Public License version 2.1 or later (LGPL).

Example license block from a source file:

/* **** BEGIN LICENSE BLOCK ****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
  * The contents of this file are subject to the Mozilla Public License Version
  * 1.1 (the "License"); you may not use this file except in compliance with
  * the License. You may obtain a copy of the License at
  * http://www.mozilla.org/MPL/
  *
  * Software distributed under the License is distributed on an "AS IS" basis,
  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  * for the specific language governing rights and limitations under the
  * License.
  *
  * The Original Code is part of dcm4che, an implementation of DICOM(TM) in
  * Java(TM), hosted at http://sourceforge.net/projects/dcm4che.
  *
  * The Initial Developer of the Original Code is
  * <snip>
  * Portions created by the Initial Developer are Copyright (C) 2002-2006
  * the Initial Developer. All Rights Reserved.
  *
  * Contributor(s):
  * <snip>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either the GNU General Public License Version 2 or later (the "GPL"), or
  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  * in which case the provisions of the GPL or the LGPL are applicable instead
  * of those above. If you wish to allow use of your version of this file only
  * under the terms of either the GPL or the LGPL, and not to allow others to
  * use your version of this file under the terms of the MPL, indicate your
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * **** END LICENSE BLOCK **** */