735 ILCS 5/15-1210
"Nonrecord claimant" means any person (i) who has or claims to have an interest in mortgaged real estate, (ii) whose name or interest, at the time a notice of foreclosure is recorded in accordance with Section 15-1503, is not disclosed of record either (1) by means of a recorded notice or (2) by means of a proceeding which under the law as in effect at the time the foreclosure is commenced would afford constructive notice of the existence of such interest and (iii) whose interest falls in any of the following categories: (1) right of homestead, (2) judgment creditor, (3) beneficial interest under any trust other than the beneficial interest of a beneficiary of a trust in actual possession of all or part of the real estate or (4) mechanics' lien claim. Notwithstanding the foregoing, for the purpose of this Article no proceeding shall be deemed to constitute constructive notice of the interest of any nonrecord claimant in the mortgaged real estate unless in the proceeding there is a legal description of the real estate sufficient to identify it with reasonable certainty. The classification of any person as a nonrecord claimant under the foregoing definition shall not be affected by any actual notice or knowledge of or attributable to the mortgagee.
735 ILCS 5/15-1210