German uses four letters which do not exist in English:
The umlauts (“Umlaute,, der Umlaut”)
äÄ, öÖ, üÜ
and the special character, or ligature, “Eszett“
which only exists in lower case.
This raises some problems: When German names or words occur in foreign (e.g. English) texts, the umlauts are often replaces by the underlying straight letters, i.e. aA, oO, uU. For instance, English-speaking newspapers and agencies would write about the former German chancellor “Schroder” and the former Austrian chancellor “Schussel”. This is not the best way to treat these names.
Having no umlauts available for typing and printing is an issue which was present virtually since the invention of the typewriter. Hence a convention has developped on how to handle this case. The rule reads:
If no umlauts are available, use the underlying letter followed by an “e”.
If no ß is available, replace it by “ss”.
It is important that the umlauts are not just letters with accents, but letters on their own. This is obvious if you consider their pronunciation. Actually, the two little dashes above the base letter are the remainders of an old-style letter “e”.
This leads to the following replacement table:
Hence if your write a German text without having the special German characters at your disposal, the two politicians should be called “Schroeder” and “Schuessel”.
It should be noted that Switzerland and Liechtenstein have stopped using the “Eszett” – if you are Swiss and have to write texts in both German and French, it is understanding that you would bargain for a single key. So basically the condition of the second rule is always satisfied there: No “Eszett” available, hence write double “s”.