I was working with the ILP project which contains two modules that I had suggested be renamed to ilp_target and ilp_concern; however, then we discovered that it chokes with /course/mod.php because the variable must be a PARAM_ALPHA which excludes the underscore (_). For consistency, it would be good if modules could have the underscore. Tablenames, blocks, function names all allow the use of the underscore so this issue caught me by surprise.

I'm filing this under course since that is where I found it but it may be more far reaching. Since Petr indicated that the issue is not trivial and that we may be able to address it in 2.0 I am initially assigning to him.