diff --git a/README.txt b/README.txt
index 55477bb..78f3054 100755
--- a/README.txt
+++ b/README.txt
@@ -2,65 +2,25 @@
==============================
TEACHING_SHARED
-This variable specifies the path to the top level of the teaching shared
-directory hierarchy, whereever you happen to have put it (e.g., on my
-machine this is set to "/Users/nstanger/Documents/Teaching/Shared").
+This variable specifies the path to the top level of the teaching shared directory hierarchy, whereever you happen to have put it (e.g., on my machine this is set to "/Users/nstanger/Documents/Teaching/Shared").
ALL_PAPERS_ROOT
-This variable specifies the path to the top level directory for all
-papers taught, i.e., the directory that contains the individual paper
-directory hierarchies. This assumes that you have all your current paper
-directories contained within a single hierarchy. If you don't, you're in
-trouble :) For example, on my machine this is set to
-"/Users/nstanger/Documents/Teaching/2005" (which contains directories
-INFO212, INFO321, ...).
+This variable specifies the path to the top level directory for all papers taught, i.e., the directory that contains the individual paper directory hierarchies. This assumes that you have all your current paper directories contained within a single hierarchy. If you don't, you're in trouble :) For example, on my machine this is set to "/Users/nstanger/Documents/Teaching" (which contains symbolic links to the current directories for INFO212, INFO321, ...).
HANDBOOK_INSTALL_ROOT
-This variable specifies the path to the top level directory on the web
-server, under which the files for this paper will be installed (that is,
-the directory that contains the individual paper directory hierarchies).
-Under Windows this would typically point to "\\INFO-NTS-12\DBCourses$"
-(but this may require munging depending on how UNC paths are dealt
-with). On my machine this is set to "/Volumes/DBCOURSES$", because this
-is where the share gets mounted.
+This variable specifies the path to the top level directory on the web server, under which the files for this paper will be installed (that is, the directory that contains the individual paper directory hierarchies). Under Windows this would typically point to "\\INFO-NTS-12\DBCourses$" (but this may require munging depending on how UNC paths are dealt with). On my machine this is set to "/Volumes/DBCOURSES$", because this is where the share gets mounted.
XSLT
-This variable specifies your preferred XSLT processor. Currently the
-valid options are "saxon" for SAXON 6.5.x, "xalan-c" for the C++
-implementation of Xalan and "xalan-j" for the Java implementation of
-Xalan (weirdly, the latter two have different command line options). For
-example, on my machine this is set to "saxon".
+This variable specifies your preferred XSLT processor. Currently the valid options are "saxon" for SAXON 6.5.x, "saxon-b" for SAXON-B 9.x, "xalan-c" for the C++ implementation of Xalan and "xalan-j" for the Java implementation of Xalan (weirdly, the latter two have different command line options). For example, on my machine this is set to "saxon-b".
Including content files
=======================
-To simulate the effect of XML fragment inclusion (which isn't supported
-in any software yet), we use ASP like tags in the document files to mark where content
-files should be inserted. These tags look something like this:
+Content files are included using XML includes. Source files are processed by xmllint (a utility that comes with libxml) to produce an intermediate XML file that contains all of the included fragments. This is then processed normally. Paths in XML includes should always be relative to the current directory, since we can't predict where in the file system hierarchy the source will be.
-<@INC[DBMS/Q_What_is_a_DBMS.xml]@>
+A typical include might looks something like this:
-What the makefile does is run a Perl script to replace each of these
-tags with the content of the file specified by the include path (this
-path is relative to the root directory of the paper + the section name,
-e.g., $(ALL_PAPERS_ROOT)/INFO212/Tutorials).
+
-A problem can arise if one of these tags occurs inside an XML comment, e.g.:
-
-
-
-This is a problem if the content file Q_What_is_a_DBMS.xml also contains
-XML comments. Comments cannot be nested in XML, and the XSLT processor
-will complain bitterly. The solution is to "neuter" the include tag, by
-changing it in such a way that the Perl script will no longer recognise
-it, e.g.:
-
-
-
-Just remember to change it back when you un-comment the inclusion, or
-the XSLT processor will complain about malformed XML tags :)
+All fragments are represented by an XML document of class "fragment". The outermost element is stripped off by the XPath expression in the xpointer attribute.