Discussion:

1 => Reference is the same as many-to-one, for example References(x => x.Store); // many x in a store

HasMany(x => x.Staff).Inverse().Cascade.All();

HasMany creats one-to-many relationship with Employee (one Store to many Employees), which is the other side of the Employee.Store relationship.

2 => Taking log from NHibernate

If you use NHibernate  with extension, by default NHIbernate will produce huge debug logs. If you want to get logs from your own extension then it will be difficult. Following is a way to keep only error message and filter out other message from NHibernate

<log4net>
  <root>
    <level value="ALL" />
    <appender-ref ref="file" />
  </root>
 <logger name="NHibernate">
   <level value="ERROR" />
 </logger>
 <logger name="NHibernate.SQL">
   <level value="ERROR" />
 </logger>
  <appender name="file" type="log4net.Appender.RollingFileAppender">
    <file value="logfile.log" />
    <appendToFile value="true" />
    <rollingStyle value="Size" />
    <maxSizeRollBackups value="5" />
    <maximumFileSize value="10MB" />
    <staticLogFileName value="true" />    
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%date [%thread] %level %logger - %message%newline" />
    </layout>
  </appender>
</log4net>

3 => log file path where the file will be generated

We can control the log file path of NHibernate by the following way, we shall put the expected directory in the log file

<file value="c:\\temp\\logfile.log" />