definiens: shall mean the occurrence of any of the following with respect to any XOMA Entity : ( a)an involuntary proceeding shall be commenced or an involuntary petition shall be filed in a court of competent jurisdiction seeking ( i ) re lief in respect of such XOMA Entity or any Subsidiary, or of a substantial part of the propert y of such XOMA Entity or any Subsidiary, under any Bankruptcy Law now or hereafter in effect, ( ii ) the appointment of a receiver, trustee, custodian, sequestrator, conservator or similar official for s uch XOMA Entity or any Subsidiary or for a substantial part of the property of such XOMA Entit y or any Subsidiary, ( iii ) the winding- up or liquidation of such XOMA Entity or any Subsidiary, which proceeding or petition shall continue undismissed for 90 calendar days or ( iv ) an order o f a court of competent jurisdiction approving or ordering any of the foregoing shall be entered ; or ( b)such XOMA Entity shall ( i ) voluntarily commence any proceeding or file any petition seeking relief under any Bankruptcy Law now or here after in effect, ( ii ) apply for the appointment of a receiver, trustee, custodian, sequestrator, conse rvator or similar official for such XOMA Entity or for a substantial part of the property of such XOMA Entity, ( iii ) fail to contest in a timely and appropriate manner any proceeding or the filing of any petition described in clause ( a ) of this definition, ( iv ) file an answer admitting the mater ial allegations of a petition filed against it in a ny proceeding described in clause ( a ) of this definiti on, ( v ) make a general assignment for the benefit o f creditors or ( vi ) wind up or liquidate ( except as p ermitted under this Agreement ) ; or ( c)such XOMA Entity shall take any action in furthe rance of or for the purpose of effecting the foregoing ; or ( d)such XOMA Entity shall admit in writing its inab ility, or fail generally, to pay its debts as they become due