e graphs
	    let pdfgraph = d3.select(this)
		.append("svg")
		.attr("id", "pdfgraph")
		.attr("width", wsvg)
		.attr("height", hsvg)
		.append("g")
		.attr("transform", "translate("+margin.left+","+margin.top+")");

	    // If there is no kde field in the data [serie], some note
	    // is written in the svg window.
	    if (!('kde' in serie)) {
		pdfgraph.append("text")
		    .attr("x", (margin.left+margin.right+wsvg)/2)
		    .attr("y", (margin.top+margin.bottom+hsvg)/2)
		    .attr("class", "warning")
