--- mod_headers.c.2.2.25        2013-09-25 14:51:42.154723094 -0700
+++ mod_headers.c       2013-09-25 14:07:11.806816257 -0700
@@ -172,6 +172,25 @@
 {
     return apr_psprintf(r->pool, "t=%" APR_TIME_T_FMT, r->request_time);
 }
+static const char *header_request_utime(request_rec *r, char *seconds)
+{
+    apr_time_t base;
+    apr_time_t additional;
+    apr_time_t expires;
+    int additional_sec;
+    char *timestr;
+
+    base = r->request_time;
+    additional_sec = atoi(seconds);
+    additional = apr_time_from_sec(additional_sec);
+    expires = base + additional;
+    if (expires < r->request_time) {
+         expires = r->request_time;
+    }
+    timestr = apr_palloc(r->pool, APR_RFC822_DATE_LEN);
+    apr_rfc822_date(timestr, expires);
+    return timestr;
+}
 
 /* unwrap_header returns HDR with any newlines converted into
  * whitespace if necessary. */
@@ -854,6 +873,7 @@
     register_format_tag_handler("t", (const void *)header_request_time);
     register_format_tag_handler("e", (const void *)header_request_env_var);
     register_format_tag_handler("s", (const void *)header_request_ssl_var);
+    register_format_tag_handler("u", (const void *)header_request_utime);
 
     return OK;
 }