https://www.w3schools.com/jsrEF/met_document_createcomment.asp
HTML DOM Document createComment() Method
Well organized and easy to understand Web building tutorials with lots of examples of how to use HTML, CSS, JavaScript, SQL, Python, PHP, Bootstrap, Java, XML...
html domdocumentcreatecommentmethod
https://www.php.net/manual/de/domdocument.createcomment.php
PHP: DOMDocument::createComment - Manual
Create new comment node
phpdomdocumentcreatecommentmanual