Currently, the following input encodings are available.
Note that it can happen that some input encoding characters are not available for a particular output device. For example, saying
groff -Tlatin1 -mlatin9 ...
fails if you use the Euro character in the input. Usually, this limitation is present only for devices which have a limited set of output glyphs (e.g. -Tascii and -Tlatin1); for other devices it is usually sufficient to install proper fonts which contain the necessary glyphs.
Due to the importance of the Euro glyph in Europe, the groff package now comes with a PostScript font called freeeuro.pfa which provides various glyph shapes for the Euro. In other words, latin-9 encoding is supported for the -Tps device out of the box (latin-2 isn't).
By its very nature, -Tutf8 supports all input encodings; -Tdvi has support for both latin-2 and latin-9 if the command line -mec is used also to load the file ec.tmac (which flips to the EC fonts).