@EdBoatConnoisseur The GPLv2 license text leaves it ambiguous whether the software is licensed -only or -or-later, but it gives an example license header to license -or-later;
one line to give the program's name and an idea of what it does.
Copyright (C) yyyy name of author

This program 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
of the License, or (at your option) any later version.

This program 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 program; if not, see
<https://www.gnu.org/licenses/>.


Even though you should not, you can modify it to license -only;
one line to give the program's name and an idea of what it does.
Copyright (C) yyyy name of author

This program 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; only version 2 of the License.

This program 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 program; if not, see
<https://www.gnu.org/licenses/>.

If you're really lazy, you can just add a SPDX header and a copyright line;
// SPDX-License-Identifier: GPL-2.0-or-later
// Copyright (C) yyyy name of author

// SPDX-License-Identifier: GPL-2.0-only
// Copyright (C) yyyy name of author


(Yes, some clowns "helpfully" add a SPDX header that is just "GPL-2.0").

Note that the SPDX header has no legal significance, although it does let people know what the license is.