The following tag of JSTL can be used to set a value to a variable in a request scope.
I tested the following page in Tomcat 5.59, JSP 2.0 and JSTL 1.1. It ran without any errors.
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<c:set var="value" scope="request" value="someValue"/>
<c:out default="None" escapeXml="true" value="${not empty value ? value : 'None'}" />
<c:out default="None" escapeXml="true" value="${empty value ? 'None' : value}" />
<c:set var="value" scope="request" value="" />
<br/>
<c:out default="None" escapeXml="true" value="${not empty value ? value : 'None'}" />
<c:out default="None" escapeXml="true" value="${empty value ? 'None' : value}" />