How do i mapping System.Guid type on NHibernate.

ie.
<id name="id" column="IS_TRK" length="4" access="field"
type="System.Guid>
<generator class="assigned" />
</id>

if you mean for pk, something like
<id name="Id" column="Id" type="guid">
<generator class="guid" />
</id>
..or more preferably if you want some sequence on them for faster inserts..

<id name="Id" column="Id" type="guid.comb">
<generator class="guid" />
</id>


/Roger

Here's how I defined all of my GUIDs:

<id name="DeliveryId" type="System.Guid" column="DeliveryId" unsaved-value="00000000-0000-0000-0000-000000000000">
<generator class="guid" />
</id>