Fluent NHibernate Mapping Question

Question

Hi, We have the following situation: Consider a Contract object that has a GUID primary key and a unique key (for legacy issues). This Contract should be mapped on the Contracts table. Now, we have Operation, which has a GUID primary key, the unique key of the contract, and other properties. For each contract there are many operations. We want to save the Operation in the Operations table.

Basically, Contracts should look like:

GUID     UniqueKey
.....       123
.....       212

Operations should look like:

GUID       UniqueKey ....
....         123      ....
....         123       ...
....         123       ...
....         212        ...
....         212        ....

How can we mapp this using Fluent NHibernate?