(a) The word applicant, as used in this chapter, refers to the person for whose relief the application for a writ of habeas corpus is presented.
(b) An application for a writ of habeas corpus may be signed and presented on behalf of an applicant by any person, who shall be referred to as the petitioner.
(c) A petitioner is not a party to a proceeding under this chapter.
(d) A petitioner who is not the applicant's attorney may not take any additional actions on behalf of the applicant that would constitute the practice of law.