Name Suffix, is there a particular order for JR SR I , II?

The most common name suffixes are senior and junior, limited chiefly to American usage, which may be written with a capital first letter (Sr.) or in lower case (jr.) following the person’s name (with or without an interceding comma). The term ‘junior’ is only correctly used if a child is given exactly the same name as his or her parent.[citation needed] (See, for example, Emily Post's Etiquette by Elizabeth L. Post 1985(?) When the suffixes are spelled out in full, they are always written with the first letter in lower case. Social name suffixes are far more frequently applied to men than to women. In French, the designations for a father and son with the same name are père (‘father’) and fils (‘son’).

Sons with a different middle name or initial may also be called Junior. An example is Ronald P. Reagan, the son of the late U.S. president, who is still titled junior even though his middle name, Prescott, differs from his late father’s middle name, which was Wilson. This notwithstanding, a son may sometimes be nicknamed "Junior" even if he is not titled as such, because "Junior" is a popular familial nickname in the United States. One instance of this is George W. Bush, who is nicknamed Junior by his family.

MORE: look at source below. Sorry am getting an error and wont let me post URL.

it is at wikipedia

Name Suffix Order