I don't known what products you have maintained but I've seen that large software products have a tendency to function as embedded-language magnets. Sometimes

I don't known what products you have maintained but I've seen that large software products have a tendency to function as embedded-language magnets. Sometimes the languages are beautiful domain-specific things that work out of the box and expose a very complex configuration setup in portable format to any platform. In the worst case they are the most horrible hodge-podge where one party was supposed to do one thing without told what the end result should be, then another party took the existing work and made it work. I'm using language here in the most wide meaning, thus it includes ad-hoc configuration scripts, inhouse schema parsers, and in-code abstract syntax trees. This is really beautiful and elegant. First, it does not make my eyes bleed. Second, it does not make me vomit. (I'm only half kidding. The things out in production... shudders). Third, s-expressions are a succint and extendable way to store configurations. s-expressions are just as portable as XML. Sure, you don't get the xsd schema to verify existing data ... but then again, how many ad-hoc xml configuration files have a schema to go with them.