Defines all the errors ANTLR can generator for both the tool and for issues with a grammar. Here is a list of language names: http://ftp.ics.uci.edu/pub/ietf/http/related/iso639.txt Here is a list of country names: http://www.chemie.fu-berlin.de/diverse/doc/ISO_3166.html I use constants not strings to identify messages as the compiler will find any errors/mismatches rather than leaving a mistyped string in the code to be found randomly in the future. Further, Intellij can do field name expansion to save me some typing. I have to map int constants to template names, however, which could introduce a mismatch. Someone could provide a .stg file that had a template name wrong. When I load the group, then, I must verify that all messages are there. This is essentially the functionality of the resource bundle stuff Java has, but I don't want to load a property file--I want to load a template group file and this is so simple, why mess with their junk. I use the default Locale as defined by java to compute a group file name in the org/antlr/tool/templates/messages dir called en_US.stg and so on. Normally we want to use the default locale, but often a message file will not exist for it so we must fall back on the US local. During initialization of this class, all errors go straight to System.err. There is no way around this. If I have not set up the error system, how can I do errors properly? For example, if the string template group file full of messages has an error, how could I print to anything but System.err? TODO: how to map locale to a file encoding for the stringtemplate group file? ST knows how to pay attention to the default encoding so it should probably just work unless a GUI sets the local to some chinese variation but System.getProperty("file.encoding") is US. Hmm...