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. 44. The method of claim 42 , wherein the determining includes finding that there are no methods in the partial transformation file subtree or the hierarchical data file subtree to perform actions other than those performed by applying the partial transformation file subtree.