In article , Wolf K
wrote:

[...] The internet works because the necessary data for routing the
data packets are inside the data packet, not external. That principle
should apply to all forms of data. Including programs, but that's a
another issue. mime headers say otherwise.
I don't see the relevance of your remark.

you mangled the quoting and you don't understand the issues.

AIUI, each data packet includes an ID to ensure that the intended
recipient computer can snag it from the data stream, and assemble the
packets in correct order, including the MIME header at the start of the
data. If you want to quibble about whether the ID data is inside the
packet or not, go ahead, quibble. Anything to keep you happy.

the mime headers are *not* part of the actual data. they *describe* the
data that is sent.

if that description is incorrect or non-existent, problems occur.

for example, a misconfigured web server often serves a binary file as
the default text, causing it to display garbled characters in the
browser window rather than initiate a file download. forcing a download
(option/alt click the link) usually results in a valid file.

sometimes the mime headers are wrong. i know of one web site that has
several pdf files for download, which when downloaded end up as .exe.
renaming them to pdf fixes the problem locally, but the real problem is
the mime type on the server is set wrong. the actual data is
unaffected.