From http://msdn.microsoft.com/en-us/library/ms174979.aspx"A column of type varchar(max) can participate in a FOREIGN KEY constraint only if the primary key it references is also defined as type varchar(max)."Well I suppose technically it is correct but AFAIK it is not possible to create a PK with such a column so this can never arise. I presume that this is intended to make the point that the length of varchar columns must be the same on both sides of the relationship.
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