Who is authorized to sign the Form 5558 for an extension?

"The person who signs this form may be an employer, plan sponsor, or plan administrator filing a Form 5500, 5500-EZ, or 5330, a disqualified person filing Form 5330, an attorney or certified public accountant qualified to practice before the IRS, a person enrolled to practice before the IRS, or a person holding a power of attorney."

Thanks Harwood