Version 0.94 of breqn.sty (May 2002) has a small patch to fix a bug that shows up when (a) flexisym is not explicitly loaded before breqn and (b) breqn is not loaded with the "mathstyleoff" option. This version of breqn.sty is not intended to be the official beta release because group alignment and the darray environment remain insufficiently addressed. In version 0.93 (September 2001) I tracked down and eliminated a number of significant bugs in the single-equation cases. I also added a mathstyle package (called from flexisym.sty) that activates ^ and _ to eliminate problems from sub/sup objects that appear from the user's point of view to be atomic but that from TeX's math atom point of view are composite. It appears to me that this will become inevitable at some point down the road and therefore it is better to start with it now so that some of the compatibility problems with other packages can begin to be addressed. For starters, after the mathstyle package is loaded, any subsequently loaded package that uses characters such as ^^J or ^^M will tend to run into trouble. A mathstyle-aware package will (a) need to save/restore the catcodes of ^ and _, and (b) use \mathsub and \mathsup if it has any definitions that require sub or sup operations. (I have a separate package "pcatcode" in the works that provides facilities to help with this, since the catcode problem is a more general problem already in need of a solution for many other packages, e.g., amsmath (double-quote character); but pcatcode isn't quite ready for release yet.) For the time being you will probably want to load flexisym & breqn after other packages, as much as possible. What I'm currently using in my test files is along the lines of \usepackage[cmbase]{flexisym} \usesymbols{msabm} \usepackage[debug]{breqn} \setkeys{breqn}{compact} You can turn off the active catcodes of ^ and _ by using a "mathstyleoff" option: \usepackage[mathstyleoff,cmbase]{flexisym} In breqn094b.zip I have also included a couple of dvi files documenting to some extent the algorithms that I am trying to implement. 2002-05-29 Michael Downes mjd@ams.org