Taming the Task of Checking
Taming the Task of Checking for Terrorists' Names: "[...] Take, for instance, the name "Abd al-Rahman," which can be a given name or a surname, depending on its culture of origin. When transliterated from the Arabic into Latin characters, the name has three parts, the first two of which are prefixes for Rahman, meaning "slave of" or "servant of."
But when an English speaker hears the name, it tends to sound like "Abdurrahman." A person writing it down based simply on how it sounds could easily spell it as one word and in a way that shares few characters with the transliterated version.
In some databases, "Abd" or "al" might be stored in fields for first or middle names, or the name could be written as "Abdurrahman" or "Abdurahman" all in one field, or "Abdul Rahman" in two fields. There are endless variations, even assuming no typos."