WordPress/wp-includes/blocks/heading/block.json

{
	"apiVersion": 2,
	"name": "core/heading",
	"category": "text",
	"attributes": {
		"textAlign": {
			"type": "string"
		},
		"content": {
			"type": "string",
			"source": "html",
			"selector": "h1,h2,h3,h4,h5,h6",
			"default": ""
		},
		"level": {
			"type": "number",
			"default": 2
		},
		"placeholder": {
			"type": "string"
		}
	},
	"supports": {
		"align": [ "wide", "full" ],
		"anchor": true,
		"className": false,
		"color": {
			"link": true
		},
		"fontSize": true,
		"lineHeight": true,
		"__experimentalSelector": {
			"core/heading/h1": "h1",
			"core/heading/h2": "h2",
			"core/heading/h3": "h3",
			"core/heading/h4": "h4",
			"core/heading/h5": "h5",
			"core/heading/h6": "h6"
		},
		"__unstablePasteTextInline": true
	}
}