--- trunk/doc/book/Makefile	2003-09-21 01:47:01.000000000 -0400
+++ trunk/doc/book/Makefile	2003-09-21 01:47:01.000000000 -0400
@@ -1,5 +1,9 @@
 XSLTPROC = xsltproc
-INSTALL_DIR = $(DESTDIR)/usr/share/doc/subversion
+ifeq ($(INSTALL_DIR),)
+INSTALL_DIR := $(DESTDIR)/usr/share/doc/subversion
+else
+INSTALL_DIR := $(DESTDIR)$(INSTALL_DIR)
+endif
 INSTALL = install
 
 ## You shouldn't normally need to edit anything below here.
@@ -29,7 +33,9 @@
 MDOCS_ALL_SOURCE = $(MDOCS_DIR)/*.xml
 MDOCS_INSTALL_DIR = $(INSTALL_DIR)/misc-docs
 
-XSL_DIR = ${BOOK_TOP}/tools/xsl
+ifeq ($(XSL_DIR),)
+XSL_DIR := ${BOOK_TOP}/tools/xsl
+endif
 XSL_FO = ${BOOK_TOP}/tools/fo-stylesheet.xsl
 XSL_HTML = $(XSL_DIR)/html/docbook.xsl
 XSL_HTML_CHUNK = $(XSL_DIR)/html/chunk.xsl