email me at one of the addresses above or consult the Free Software
Foundation's website at www.fsf.org, or the GNU Project website at
www.gnu.org.
+
+
+Some of the source files use the SPDX licence indication convention.
+For example, you may see:
+ SPDX-License-Identifier: GPL-3.0-or-later
+This should be read as a licence grant, as is conventional.