I recently ran into a case where I had to query an Entity in SalesLogix to find records where a user was in any one of three fields.  ICriteria has an Or operand but that is for comparing only two fields.  So how do you do three?  With Disjunction.  Here is an example:

Sage.Platform.RepositoryHelper<Sage.Entity.Interfaces.IAccount> repository =
Sage.Platform.EntityFactory.GetRepositoryHelper<Sage.Entity.Interfaces.IAccount>();
Sage.Platform.Repository.ICriteria criteria = repository.CreateCriteria();
criteria.Add(repository.EF.Disjunction()
    .Add(repository.EF.Eq("CreateUser", CurrentEntity.Id.ToString()))
    .Add(repository.EF.Eq("ModifyUser", CurrentEntity.Id.ToString()))
    .Add(repository.EF.Eq("AccountManagerId", CurrentEntity.Id.ToString())));
System.Collections.Generic.IList<Sage.Entity.Interfaces.IAccount> accounts = criteria.List<Sage.Entity.Interfaces.IAccount>();