Dmg:

Following this rational, would it be possible to recommend something in the line of:
BEGIN_LICENSE
This file is licensed under the <SPDX_LICENSE_IDENTIFIER>
For more information see URL-TO-SPDX-WEB-SITE-WITH-iNFO
END_LICENSE
that makes three things explicit:

* It says where the license info in -file is (BEGIN, END_LICENSE)
* It explicitly states the file is licensed under the given licence
* It says where to get more information to understand what it means.

Jack's way of doing it, by just naming the license feels too cryptic to me if I am reading the header, and does not explicitly state it is the license under which the file is made available to others

From a programmer's perspective I think the "cryptic" approach is FAR superior. There are lots of tools that can quickly examine files and return text with the pattern "SPDX-License-Identifier: ", and other tools that can trivially process the stuff after it. The above alternative is more work to process, and humans don't like unnecessary work :-).

If you want more boilerplate with the goal of enforceability, you might try a format that's trivial to process, e.g.:

SPDX-License-Notice: This file is licensed under the following license(s):
SPDX-License-Identifier: MIT
SPDX-License-More-Information: http://wiki.spdx.org/

--- David A. Wheeler