Onomastics

Onomastics=the branch of lexicology that studies the forms and origins of proper name, and naming practices.

The word is derived from the Greek word ὄνομα (onoma), meaning name. Toponymy or toponomastics, the study of place names, is one of the principal branches of onomastics. Anthroponomastics is the study of personal names.

Wikipedia

# foreign characters: mueller or müller, juerg or jürg. note that some systems use juerg instead of jürg cause of character sets, and some ppl need to be written that way. If your name is written "juerg müller" in your passport, you can't go and open a bank account as "jürg müller".
# nicknames: peggy for margaret, bill for william.
# short forms: b. gates for william gates (ouch!).
# localization: andreas from germany, andré from france, andrei/andrej from russia and andrea from italy is the same name, just translations. moved to the us, and all become andrew because those americans can't make a difference. mr. hundertwasser may also become hundredwater or so. with italians 'andrea' we have another problem, cause in germany andrea exists too, but is feminin.
# name families: adelheide, adelheidi. especially nowadays it's cool to invent new names, or at least new spellings. the americans might be different, having michael as #1 baby name since 1964 *shakes head*. in this example, heidi may be a different family member and a nickname, both is possible.
# titles and qualifiers: dr. prof. ph.d. nat. ... may be written as "dr. smith" or "smith, dr."
# prefixes: Di Caprio, D'Agostino, Al Afif, Mc Donald, ...
# married: "peggy smith" becomes "margaret johnson". bingo. she may aswell become "peggy johnson-smith" or so, which leaves us a chance to still find her.

From Blueshoes

Further readings on onomastics

American Name Society