diff -ruN subversion/include/svn_subst.h subversion/include/svn_subst.h
--- subversion/include/svn_subst.h	2009-01-26 14:30:42.000000000 +0300
+++ subversion/include/svn_subst.h	2009-04-03 21:49:30.541875000 +0400
@@ -122,16 +122,31 @@
  * Set @a *kw to a new keywords hash filled with the appropriate contents
  * given a @a keywords_string (the contents of the svn:keywords
  * property for the file in question), the revision @a rev, the @a url,
- * the @a date the file was committed on, and the @a author of the last
- * commit.  Any of these can be @c NULL to indicate that the information is
- * not present, or @c 0 for @a date.
+ * the url of the root of the @a repos, the @a date the file was committed
+ * on, and the @a author of the last commit.  Any of these can be @c NULL
+ * to indicate that the information is not present, or @c 0 for @a date.
  *
  * Hash keys are of type <tt>const char *</tt>.
  * Hash values are of type <tt>svn_string_t *</tt>.
  *
  * All memory is allocated out of @a pool.
  *
- * @since New in 1.3.
+ * @since New in 1.6
+ */
+svn_error_t *
+svn_subst_build_keywords3(apr_hash_t **kw,
+                          const char *keywords_string,
+                          const char *rev,
+                          const char *url,
+                          const char *repos,
+                          apr_time_t date,
+                          const char *author,
+                          apr_pool_t *pool);
+
+/** Similar to svn_subst_build_keywords3() except that it does not
+ * supply the repository location.
+ *
+ * @deprecated Provided for backward compatibility with the 1.3 API.
  */
 svn_error_t *
 svn_subst_build_keywords2(apr_hash_t **kw,
diff -ruN subversion/libsvn_client/cat.c subversion/libsvn_client/cat.c
--- subversion/libsvn_client/cat.c	2009-02-13 23:37:02.000000000 +0300
+++ subversion/libsvn_client/cat.c	2009-04-03 21:49:30.557500000 +0400
@@ -127,10 +127,10 @@
           author = entry->cmt_author;
         }
 
-      SVN_ERR(svn_subst_build_keywords2
+      SVN_ERR(svn_subst_build_keywords3
               (&kw, keywords->data,
                apr_psprintf(pool, fmt, entry->cmt_rev),
-               entry->url, tm, author, pool));
+               entry->url, entry->repos, tm, author, pool));
     }
 
   /* Our API contract says that OUTPUT will not be closed. The two paths
@@ -160,6 +160,7 @@
   svn_string_t *keywords;
   apr_hash_t *props;
   const char *url;
+  const char *repos_root_url;
   svn_stream_t *output = out;
 
   /* ### Inconsistent default revision logic in this command. */
@@ -198,6 +199,8 @@
                                            &url, path_or_url, NULL,
                                            peg_revision,
                                            revision, ctx, pool));
+  /* Find the repos root URL */
+  SVN_ERR(svn_ra_get_repos_root2(ra_session, &repos_root_url, pool));
 
   /* Make sure the object isn't a directory. */
   SVN_ERR(svn_ra_check_path(ra_session, "", rev, &url_kind, pool));
@@ -242,10 +245,11 @@
           if (cmt_date)
             SVN_ERR(svn_time_from_cstring(&when, cmt_date->data, pool));
 
-          SVN_ERR(svn_subst_build_keywords2
+          SVN_ERR(svn_subst_build_keywords3
                   (&kw, keywords->data,
                    cmt_rev->data,
                    url,
+                   repos_root_url,
                    when,
                    cmt_author ? cmt_author->data : NULL,
                    pool));
diff -ruN subversion/libsvn_client/commit.c subversion/libsvn_client/commit.c
--- subversion/libsvn_client/commit.c	2009-02-13 18:32:52.000000000 +0300
+++ subversion/libsvn_client/commit.c	2009-04-03 21:49:30.557500000 +0400
@@ -118,9 +118,9 @@
     }
 
   if (keywords_val)
-    SVN_ERR(svn_subst_build_keywords2(&keywords, keywords_val->data,
+    SVN_ERR(svn_subst_build_keywords3(&keywords, keywords_val->data,
                                       APR_STRINGIFY(SVN_INVALID_REVNUM),
-                                      "", 0, "", pool));
+                                      "", "", 0, "", pool));
   else
     keywords = NULL;
 
diff -ruN subversion/libsvn_client/export.c subversion/libsvn_client/export.c
--- subversion/libsvn_client/export.c	2009-01-26 14:30:42.000000000 +0300
+++ subversion/libsvn_client/export.c	2009-04-03 21:49:30.557500000 +0400
@@ -197,10 +197,10 @@
           author = entry->cmt_author;
         }
 
-      SVN_ERR(svn_subst_build_keywords2
+      SVN_ERR(svn_subst_build_keywords3
               (&kw, keywords->data,
                apr_psprintf(pool, fmt, entry->cmt_rev),
-               entry->url, tm, author, pool));
+               entry->url, entry->repos, tm, author, pool));
     }
 
   /* For atomicity, we translate to a tmp file and then rename the tmp file
@@ -509,6 +509,7 @@
   /* Any keyword vals to be substituted */
   const char *revision;
   const char *url;
+  const char *repos;
   const char *author;
   apr_time_t date;
 
@@ -625,6 +626,7 @@
   fb->edit_baton = eb;
   fb->path = full_path;
   fb->url = full_url;
+  fb->repos = eb->root_url;
   fb->pool = pool;
 
   *baton = fb;
@@ -790,8 +792,8 @@
         }
 
       if (fb->keywords_val)
-        SVN_ERR(svn_subst_build_keywords2(&final_kw, fb->keywords_val->data,
-                                          fb->revision, fb->url, fb->date,
+        SVN_ERR(svn_subst_build_keywords3(&final_kw, fb->keywords_val->data,
+                                          fb->revision, fb->url, fb->repos, fb->date,
                                           fb->author, pool));
 
       SVN_ERR(svn_subst_copy_and_translate3
diff -ruN subversion/libsvn_subr/subst.c subversion/libsvn_subr/subst.c
--- subversion/libsvn_subr/subst.c	2009-01-26 14:30:42.000000000 +0300
+++ subversion/libsvn_subr/subst.c	2009-04-03 21:50:34.276250000 +0400
@@ -127,8 +127,11 @@
  * %b basename of the URL of this file
  * %d short format of date of this revision
  * %D long format of date of this revision
+ * %P path relative to root of repos
  * %r number of this revision
+ * %R root url of repository
  * %u URL of this file
+ * %_ a space
  * %% a literal %
  *
  * All memory is allocated out of @a pool.
@@ -137,12 +140,14 @@
 keyword_printf(const char *fmt,
                const char *rev,
                const char *url,
+               const char *repos,
                apr_time_t date,
                const char *author,
                apr_pool_t *pool)
 {
   svn_stringbuf_t *value = svn_stringbuf_ncreate("", 0, pool);
   const char *cur;
+  const char *relative;
   int n;
 
   for (;;)
@@ -196,6 +201,23 @@
             svn_stringbuf_appendcstr(value,
                                      svn_time_to_human_cstring(date, pool));
           break;
+        case 'P': /* relative path of this file */
+	  relative = url;
+          if (relative && repos)
+            {
+	      int len = strlen(repos);
+
+	      if (strncmp(repos, relative, len) == 0
+		  && relative[len] == '/')
+		relative += len + 1;
+	    }
+	  if (relative)
+            svn_stringbuf_appendcstr(value, relative);
+          break;
+        case 'R': /* root of repos */
+	  if (repos)
+	    svn_stringbuf_appendcstr(value, repos);
+	  break;
         case 'r': /* number of this revision */
           if (rev)
             svn_stringbuf_appendcstr(value, rev);
@@ -204,6 +226,9 @@
           if (url)
             svn_stringbuf_appendcstr(value, url);
           break;
+        case '_': /* '%_' => a space */
+          svn_stringbuf_appendbytes(value, " ", 1);
+          break;
         case '%': /* '%%' => a literal % */
           svn_stringbuf_appendbytes(value, cur, 1);
           break;
@@ -239,8 +264,8 @@
   apr_hash_t *kwhash;
   const svn_string_t *val;
 
-  SVN_ERR(svn_subst_build_keywords2(&kwhash, keywords_val, rev,
-                                    url, date, author, pool));
+  SVN_ERR(svn_subst_build_keywords3(&kwhash, keywords_val, rev,
+                                    url, "", date, author, pool));
 
   /* The behaviour of pre-1.3 svn_subst_build_keywords, which we are
    * replicating here, is to write to a slot in the svn_subst_keywords_t
@@ -279,6 +304,21 @@
                           const char *author,
                           apr_pool_t *pool)
 {
+  SVN_ERR(svn_subst_build_keywords3(kw, keywords_val, rev,
+                                    url, "", date, author, pool));
+  return SVN_NO_ERROR;
+}
+
+svn_error_t *
+svn_subst_build_keywords3(apr_hash_t **kw,
+                          const char *keywords_val,
+                          const char *rev,
+                          const char *url,
+                          const char *repos,
+                          apr_time_t date,
+                          const char *author,
+                          apr_pool_t *pool)
+{
   apr_array_header_t *keyword_tokens;
   int i;
   *kw = apr_hash_make(pool);
@@ -289,6 +329,24 @@
   for (i = 0; i < keyword_tokens->nelts; ++i)
     {
       const char *keyword = APR_ARRAY_IDX(keyword_tokens, i, const char *);
+      apr_array_header_t *keyword_tokens2;
+
+      keyword_tokens2 = svn_cstring_split(keyword, "=", TRUE /* chop */, pool);
+      if (keyword_tokens2->nelts == 2)
+        {
+          svn_string_t *custom_val;
+          const char *custom_expand;
+
+          keyword = APR_ARRAY_IDX(keyword_tokens2, 0, const char*);
+          custom_expand = APR_ARRAY_IDX(keyword_tokens2, 1, const char*);
+          if (! strcmp(custom_expand, "%H"))
+	    custom_expand = "%P %r %d %a";
+	  else if (! strcmp(custom_expand, "%I"))
+	    custom_expand = "%b %r %d %a";
+          custom_val = keyword_printf(custom_expand, rev, url, repos, date, author, pool);
+          apr_hash_set(*kw, keyword, APR_HASH_KEY_STRING, custom_val);
+          return SVN_NO_ERROR;
+        }
 
       if ((! strcmp(keyword, SVN_KEYWORD_REVISION_LONG))
           || (! strcmp(keyword, SVN_KEYWORD_REVISION_MEDIUM))
@@ -296,7 +354,7 @@
         {
           svn_string_t *revision_val;
 
-          revision_val = keyword_printf("%r", rev, url, date, author, pool);
+          revision_val = keyword_printf("%r", rev, url, repos, date, author, pool);
           apr_hash_set(*kw, SVN_KEYWORD_REVISION_LONG,
                        APR_HASH_KEY_STRING, revision_val);
           apr_hash_set(*kw, SVN_KEYWORD_REVISION_MEDIUM,
@@ -309,7 +367,7 @@
         {
           svn_string_t *date_val;
 
-          date_val = keyword_printf("%D", rev, url, date, author, pool);
+          date_val = keyword_printf("%D", rev, url, repos, date, author, pool);
           apr_hash_set(*kw, SVN_KEYWORD_DATE_LONG,
                        APR_HASH_KEY_STRING, date_val);
           apr_hash_set(*kw, SVN_KEYWORD_DATE_SHORT,
@@ -320,7 +378,7 @@
         {
           svn_string_t *author_val;
 
-          author_val = keyword_printf("%a", rev, url, date, author, pool);
+          author_val = keyword_printf("%a", rev, url, repos, date, author, pool);
           apr_hash_set(*kw, SVN_KEYWORD_AUTHOR_LONG,
                        APR_HASH_KEY_STRING, author_val);
           apr_hash_set(*kw, SVN_KEYWORD_AUTHOR_SHORT,
@@ -331,7 +389,7 @@
         {
           svn_string_t *url_val;
 
-          url_val = keyword_printf("%u", rev, url, date, author, pool);
+          url_val = keyword_printf("%u", rev, url, repos, date, author, pool);
           apr_hash_set(*kw, SVN_KEYWORD_URL_LONG,
                        APR_HASH_KEY_STRING, url_val);
           apr_hash_set(*kw, SVN_KEYWORD_URL_SHORT,
@@ -341,7 +399,7 @@
         {
           svn_string_t *id_val;
 
-          id_val = keyword_printf("%b %r %d %a", rev, url, date, author,
+          id_val = keyword_printf("%b %r %d %a", rev, url, repos, date, author,
                                   pool);
           apr_hash_set(*kw, SVN_KEYWORD_ID,
                        APR_HASH_KEY_STRING, id_val);
@@ -350,7 +408,7 @@
         {
           svn_string_t *header_val;
 
-          header_val = keyword_printf("%u %r %d %a", rev, url, date, author,
+          header_val = keyword_printf("%u %r %d %a", rev, url, repos, date, author,
                                       pool);
           apr_hash_set(*kw, SVN_KEYWORD_HEADER,
                        APR_HASH_KEY_STRING, header_val);
diff -ruN subversion/libsvn_wc/translate.c subversion/libsvn_wc/translate.c
--- subversion/libsvn_wc/translate.c	2009-02-16 09:25:05.000000000 +0300
+++ subversion/libsvn_wc/translate.c	2009-04-03 21:49:30.541875000 +0400
@@ -284,11 +284,12 @@
 
   SVN_ERR(svn_wc__entry_versioned(&entry, path, adm_access, FALSE, pool));
 
-  SVN_ERR(svn_subst_build_keywords2(keywords,
+  SVN_ERR(svn_subst_build_keywords3(keywords,
                                     list,
                                     apr_psprintf(pool, "%ld",
                                                  entry->cmt_rev),
                                     entry->url,
+                                    entry->repos,
                                     entry->cmt_date,
                                     entry->cmt_author,
                                     pool));
