You need to look up in help section or other places about the usage of the \\ in regards to names that do not follow first/middle/surname convention.

I have entered royalty and nobles without surnames in this manner:

William \\ I the Conqueror
Alfred \\ the Great

As a side note you can also use the double slashes around text to keep them in a specific arrangement. Say you have a double name that is not hyphenated, or one of those Dutch names that for some reason the system wants to ignore certain portions of.

Edward \Curran Smith\
Anna \Van der Hook\

Hope this helps!
Elizabeth