Index: modules/dav/main/mod_dav.h
===================================================================
--- modules/dav/main/mod_dav.h	(revision 814689)
+++ modules/dav/main/mod_dav.h	(working copy)
@@ -2419,6 +2419,31 @@
     const dav_hooks_liveprop *provider;  /* the provider defining this prop */
 } dav_elem_private;    
 
+/* --------------------------------------------------------------------
+**
+** DAV OPTIONS HOOKS
+*/
+#define DAV_OPTIONS_EXTENSION_GROUP "dav_options"
+
+typedef struct dav_hooks_options
+{
+    dav_error* (*dav_header)(request_rec *r,
+                             const dav_resource *resource,
+                             apr_text_header *phdr);
+    
+    dav_error* (*dav_method)(request_rec *r,
+                             const dav_resource *resource,
+                             apr_text_header *phdr);
+    
+    void *ctx;                              
+} dav_hooks_options;
+
+extern DAV_DECLARE(const dav_hooks_options *) dav_get_options_hooks(const char *name);
+
+extern DAV_DECLARE(void) dav_options_register_hooks(apr_pool_t *p, 
+                                                    const char *name,
+                                                    const dav_hooks_options *provider);
+
 #ifdef __cplusplus
 }
 #endif
Index: modules/dav/main/mod_dav.c
===================================================================
--- modules/dav/main/mod_dav.c	(revision 814689)
+++ modules/dav/main/mod_dav.c	(working copy)
@@ -59,7 +59,9 @@
 
 #include "mod_dav.h"
 
+#include "ap_provider.h"
 
+
 /* ### what is the best way to set this? */
 #define DAV_DEFAULT_PROVIDER    "filesystem"
 
@@ -1575,6 +1577,9 @@
     const apr_xml_elem *elem;
     dav_error *err;
 
+    apr_array_header_t *extensions;
+    ap_list_provider_names_t *entry;
+
     /* resolve the resource */
     err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                            &resource);
@@ -1603,6 +1608,23 @@
     if (binding_hooks != NULL)
         dav_level = apr_pstrcat(r->pool, dav_level, ",bindings", NULL);
 
+    /* DAV header additions registered by external modules */
+    extensions = ap_list_provider_names(r->pool, DAV_OPTIONS_EXTENSION_GROUP, "0");
+    entry = (ap_list_provider_names_t *)extensions->elts;
+	
+    for (i = 0; i < extensions->nelts; i++, entry++) {
+	const dav_hooks_options *options = 
+	    dav_get_options_hooks(entry->provider_name);
+	
+	if (options && options->dav_header) {
+	    apr_text_header hoptions = { 0 };
+	    
+	    options->dav_header(r, resource, &hoptions);
+	    for (t = hoptions.first; t && t->text; t = t->next)
+		dav_level = apr_pstrcat(r->pool, dav_level, ",", t->text, NULL);
+	}   
+    }
+
     /* ###
      * MSFT Web Folders chokes if length of DAV header value > 63 characters!
      * To workaround that, we use separate DAV headers for versioning and
@@ -1746,6 +1768,23 @@
         apr_table_addn(methods, "SEARCH", "");
     }
 
+    /* additional methods registered by external modules */
+    extensions = ap_list_provider_names(r->pool, DAV_OPTIONS_EXTENSION_GROUP, "0");
+    entry = (ap_list_provider_names_t *)extensions->elts;
+    
+    for (i = 0; i < extensions->nelts; i++, entry++) {
+	const dav_hooks_options *options = 
+	    dav_get_options_hooks(entry->provider_name);
+	
+	if (options && options->dav_method) {
+	    apr_text_header hoptions = { 0 };
+	    
+	    options->dav_method(r, resource, &hoptions);
+	    for (t = hoptions.first; t && t->text; t = t->next)
+		apr_table_addn(methods, t->text, "");
+	}    
+    }
+
     /* Generate the Allow header */
     arr = apr_table_elts(methods);
     elts = (const apr_table_entry_t *)arr->elts;
Index: modules/dav/main/providers.c
===================================================================
--- modules/dav/main/providers.c	(revision 814689)
+++ modules/dav/main/providers.c	(working copy)
@@ -31,3 +31,16 @@
 {
     return ap_lookup_provider(DAV_PROVIDER_GROUP, name, "0");
 }
+
+DAV_DECLARE(void) dav_options_register_hooks(apr_pool_t *p, 
+                                             const char *name,
+                                             const dav_hooks_options *provider)
+{
+    ap_register_provider(p, DAV_OPTIONS_EXTENSION_GROUP, name, "0", provider);
+}
+
+DAV_DECLARE(const dav_hooks_options *) dav_get_options_hooks(const char *name)
+{
+    return ap_lookup_provider(DAV_OPTIONS_EXTENSION_GROUP, name, "0");
+}
+