Filter by UserId

Hi,

Could you please tell me what means the following syntax from list's schema.xml:

<Neq><FieldRef Name="UserField" LookupId="True" /><Value Type="Lookup">0</Value></Neq>

Is this the same as:

<Neq><FieldRef Name="UserField" LookupId="True" /><Value Type="Lookup"><UserID Type="Integer" /></Value></Neq>

?

Thank you in advance!