I’m trying to send this Telegram API message via POST:

POST /MY_BOT:MY_TOKEN/sendMessage?chat_id=MY_CHAT_ID&text=<code>0 H</code>&parse_mode=HTML

but I keep getting a 400 bad request with no more information.

I am using the code tag to get monospaced font.

The problem seems to be due to the interaction between 0 and H. Lower case H does not fail.

What is the overall issue here and how can I avoid encountering all such issues?