HTML processing instructionsAn HTML processing instruction is text enclosed by <? and >, which marks a target for further processing. They may appear anywhere in a document. They are ignored like comments when they're not recognized for a specific purpose.limitedhttps://html.spec.whatwg.org/multipage/syntax.html#processing-instructionshttps://developer.mozilla.org/docs/Web/API/ProcessingInstructionapi.ProcessingInstruction.doc_htmlapi.ProcessingInstruction.getAttributeapi.ProcessingInstruction.getAttributeNamesapi.ProcessingInstruction.hasAttributeapi.ProcessingInstruction.hasAttributesapi.ProcessingInstruction.removeAttributeapi.ProcessingInstruction.setAttributeapi.ProcessingInstruction.toggleAttributehttps://nowyoucanuse.com/features--html-processing-instructions.html