42. A method comprising: determining, for a change to a node of a hierarchical data file subtree, whether applying a partial transformation file subtree corresponding to the hierarchical data file subtree will produce a third rendering file equivalent to a difference between a first rendering file created by applying a full transformation file on a full hierarchical data file prior to the change to the node and a second rendering file created by applying the full transformation file on the full hierarchical data file after the change to the node; and producing the third rendering file by applying a partial transformation file when it is determined that applying a partial transformation file on the changed hierarchical data file will produce a third rendering file equivalent to the difference.
42. A method comprising: determining, for a change to a node of a hierarchical data file subtree, whether applying a partial transformation file subtree corresponding to the hierarchical data file subtree will produce a third rendering file equivalent to a difference between a first rendering file created by applying a full transformation file on a full hierarchical data file prior to the change to the node and a second rendering file created by applying the full transformation file on the full hierarchical data file after the change to the node; and producing the third rendering file by applying a partial transformation file when it is determined that applying a partial transformation file on the changed hierarchical data file will produce a third rendering file equivalent to the difference. 45. The method of claim 42 , wherein the determining includes finding that there are no nested subtrees within the partial transformation file subtree or the hierarchical data file subtree.