Description
The username must start with an alphabetical character and must NOT contain any other characters than alphanumerics, the underline and dash.
If you use the 'name map' you should also use these naming in the supplied extra array, because your values would get mixed up if they are in the wrong order, which is always true if you DON'T use the 'name map'!
So be warned and USE the 'name map'!
If the passwd file is shadowed, the user will be added though, but with an 'x' as password, and a PEAR_Error will be returned, too.