Patent ID: 7607099

Claim:
A method in a computer system having a memory and a processor for transforming a design tree representing a document, the method comprising: inputting by a source transform an identity-description identifying a subset of a version of the design tree and outputting by the source transform the subset of the version of the design tree identified by the input identity-description; for each of a plurality of intermediate transforms, inputting by the intermediate transform a version of the design tree and outputting by the intermediate transform a transformed version of the design tree; and inputting by the intermediate transform an identity-description identifying a subset of the transformed version of the design tree and outputting by the intermediate transform a transformed identity-description identifying a subset of the input version of the design tree wherein each intermediate transform is reversible such that forward transforms transform versions of the design tree and backward transforms transform identity-descriptions identifying subsets of versions of the design tree; and inputting by a sink transform a version of the design tree and outputting by the sink transform an identity-description identifying a subset of the input version of the design tree, wherein the transforms form a pipeline having a modular architecture starting with the source transform, continuing with the intermediate transforms, and ending with the sink transform in the forward direction and starting with the sink transform, continuing with the intermediate transforms, and ending with the source transform in the backward direction.