Hello,

This is actually a double release. Release 2.1.3 was deemed stable, and was 
retagged as 2.2.0 and became the stable branch.  There is no difference 
between 2.1.3 and 2.2.0, so the changelog for 2.2.1 is for 2.1.3->2.2.1.

Here's the release notice:

REXML is a pure Ruby XML processor inspired by the Electric XML processor 
for Java. The API is terse and intuitive, and XML processing is reasonably 
fast.  REXML lives at:

        http://www.germane-software.com/software/rexml

2.2.1: Fixed a bug in benchmark/bench.rb that kept it from running. Added 
stand_alone?() to XMLDecl as an alias for the standalone accessor. 
Improvements to the streaming API; in particular, pulling data from 
non-closing streams doesn't require passing a block size of 1 to the 
IOSource class any longer; in fact, the block size is ignored, although it 
is maintained in the API for backward compatibility. Added a user-supplied 
patch to fix the fact that not all of the DTD events were getting passed to 
the listener. Improved entity parsing. Better test suite; you can now pass 
<code>--help</code> to the main test suite to get a list of the new 
options, which include listing the available suites and listing methods in 
the suites, as well as instructions on how to run only certain suites or 
methods in suites. 

There are some implications about this if you've been using the block-size 
argument to the streaming API.  The main one is that you should see a 
significant speed improvement.  The second is that, while you don't have to 
change your old applications, you shouldn't use the block-size argument any 
longer -- it has been deprecated.

2.3.0: Development branch. Full handling of internal entities. Note that 
this complicates Text handling, and the implications are discussed in the 
Tutorial.  Further speed improvements in most areas of REXML, but most 
visibly in large document and stream processing.

Because of the new entity handling, the behavior of Text nodes has changed 
subtly, and you should be aware of this.  Please see the tutorial section 
on Text Nodes for more details.

--- SER