Ill. Admin. Code tit. 80, § 1200.70
A party may be represented by counsel or any other representative of the party's choosing. The representative shall file a Notice of Appearance with the Board referencing the case number and caption, and the postal address, email address and telephone number of the representative. Filing pleadings on behalf of a party shall be equivalent to filing a Notice of Appearance, provided the pleadings include the required information.
(Source: Amended at 40 Ill. Reg. 10892, effective August 1, 2016)