2. The method of claim 1 , wherein determining whether the characteristics of the sub-tree rooted at said each node meet the first criterion includes: determining whether a suitability metric evaluated over the sub-tree rooted at said each node exceeds a threshold value.
2. The method of claim 1 , wherein determining whether the characteristics of the sub-tree rooted at said each node meet the first criterion includes: determining whether a suitability metric evaluated over the sub-tree rooted at said each node exceeds a threshold value. 7. The method of claim 2 , further comprising automatically determining the threshold value based on capabilities of a computer that stores the XML document.