If you are upgrading an existing LaTeX 2.09 style file then we recommend freezing the 2.09 version and no longer maintaining it. Experience with the various dialects of LaTeX which existed in the early 1990's suggests that maintaining packages for different versions of LaTeX is almost impossible. It will, of course, be necessary for some organisations to maintain both versions in parallel for some time but this is not essential for those packages and classes supported by individuals: they should support only the new standard LaTeX2e, not obsolete versions of LaTeX.