Thank you Borislav!

>>I have been reading some text which indicates that to index an XML column, there must be a clustered index on the Primary Key of the table, and that the index on the XML column must be a "Primary Index".
>>
>>I understand a primary key, and I understand that a primary key can be a clustered or not-clustered index. An index can also be defined on the primary DB file, but I have not heard of 'Primary Index' before, and I am unable to pull anything up in a search for the whole term in BOL. Is there such a thing?
>>
>>Your help is greatly appriciated.
>
>From http://msdn2.microsoft.com/en-us/library/ms188783.aspx
>

>[PRIMARY] XML
>
>    Creates an XML index on the specified xml column. When PRIMARY is specified, a clustered
>index is created with the clustered key formed from the clustering key of the user table and an
>XML node identifier. Each table can have up to 249 XML indexes. Note the following when you
>create an XML index:
>
>        * A clustered index must exist on the primary key of the user table.
>        * The clustering key of the user table is limited to 15 columns.
>        * Each xml column in a table can have one primary XML index and multiple secondary XML
>          indexes.
>        * A primary XML index on an xml column must exist before a secondary XML index can be
>          created on the column.
>        * An XML index can only be created on a single xml column. You cannot create an XML index
>          on a non-xml column, nor can you create a relational index on an xml column.
>        * You cannot create an XML index, either primary or secondary, on an xml column in a
>          view, on a table-valued variable with xml columns, or xml type variables.
>        * You cannot create a primary XML index on a computed xml column.
>        * The SET option settings must be the same as those required for indexed views and
>          computed column indexes. Specifically, the option ARITHABORT must be set to ON when an
>          XML index is created and when inserting, deleting, or updating values in the xml
>          column. For more information, see SET Options That Affect Results.
>
>    For more information, see Indexes on xml Data Type Columns.
>