Can anybody please tell me that how can I define sub-clauses (Child Clauses) in Oracle Contracts (OK

I have contract whose clauses are like below:

1.ABC Section

1.1. DEF Clause

1.1.1. XYZ Sub-clause

But in the clause section I can't see any option of defining it as sub-clause. So can anybody please let me know that how can I define sub-clauses (Child Clauses).

P.S. In numbering schemes I can see different levels of numbering. So there should be some way.