function filterMarkdown( contentFilename ){
        // if (!file) return
	// special filter, done via URL, no local file (for now at least)

        if ( contentFilename.endsWith(".md") ) {
                console.log('it is a markdown file', contentFilename)

		// mereology option
		let openingOptions = filesWithMetadata[contentFilename].openingOptions
		// can be used via e.g. showFile("https://fabien.benetou.fr/?action=source",{ mereology:"whole"})

		fetch( contentFilename )
		.then( r => r.text() ).then( r => {
			console.log('markdown', r)

			console.log( "mereology", openingOptions.mereology )
			switch( openingOptions.mereology ) {
				case "whole":
					addNewNote(r, "0 1.4 -.8")
				break;
				case "section":
					r.split(/! /).map( (c,i) => addNewNote(c, "0 "+(1+i/10)+" -.8") ) // untested
				break;
				case "line":
					r.split('\n').reverse().map( (c,i) => addNewNote(c, "0 "+(1+i/10)+" -.8") )
				break;
				case "listonly":
					r.replaceAll('* ','').split('\n').map( (c,i) => addNewNote(c, "0 "+(1+i/10)+" -.8") )
					// based on pmwiki, should also work with + or -
				default:
					r.split('\n').reverse().map( (c,i) => addNewNote(c, "0 "+(1+i/10)+" -.8") )
			} 
					
			AFRAME.scenes[0].emit('markdownloaded', contentFilename)
			// to use the event consider :
			//AFRAME.scenes[0].addEventListener("markdownloaded", e => console.log(e))
		})
        }
        applyNextFilter( contentFilename )
}

sequentialFilters.push( filterMarkdown )