Each limited partnership shall have: A principal office in this State; and A resident agent. A limited partnership may designate or change its resident agent or principal office by filing for record with the Department a statement signed by one of its general partners which authorizes the designation or change. A limited partnership may change the address of its resident agent by filing for record with the Department a statement of the change signed by one of its general partners. A designation or change of a principal office or resident agent or address of the resident agent for a limited partnership under this subsection is effective when the Department accepts the statement for record. A resident agent who changes his address in the State may notify the Department of the change by filing for record with the Department a statement of the change signed by him or on his behalf. The statement shall include: The name of the limited partnership for which the change is effective; The old and new addresses of the resident agent; and The date on which the change is effective. If the old and new addresses of the resident agent are the same as the old and new addresses of the principal office of the limited partnership, the statement may include a change of address for the principal office if: The resident agent notifies the limited partnership in writing; and The statement recites that he has done so. The change of address of the resident agent or principal office is effective when the Department accepts the statement for record. A resident agent may resign by filing with the Department a counterpart or photocopy of his signed resignation. Unless a later time is specified in the resignation, it is effective: At the time it is filed with the Department, if the limited partnership has appointed a successor resident agent; or 10 days after it is filed with the Department, if the limited partnership has not appointed a successor resident agent.