Enter your full "legal" birth name as written on your original birth certificate (first, middle and last names) - even if any name was misspelled.
Enter you current full "legal" name. If you are now using an "initial" for a middle name and that "initial" represents a name - then spell out that name even though you are using an "initial" instead. A "legal" name is the full name you now go by (first, middle and last names) on your legal documents such as tax return, driver's license, retirement accounts and not some variation of that legal name.
If you do not have a middle name, just leave it blank. If your middle name is only an initial and not spelled out, then enter your middle initial only, and if you have a middle name, then enter your full middle name.
Jr., Sr., III etc. are considered to be extensions. Do not enter ANY EXTENSION added to a name; enter the NAME ONLY.
Do not use any symbols, punctation marks or numbers. Spaces should not affect the calculation and are necessary by default.