This paper addresses an XML-based design environment, which provides a powerful basis for the manipulation of hardware design descriptions. The contribution of the paper is a flexible specification entry for the definition of transformation rules, which allows a designer to specify transformations by his/her own without having XML expertise. The specification entry provides a guided and graphically supported mechanism to define transformation rules. This opens up a new approach, in which the specification and verification of a transformation rule is carried out by using simple design examples, to be applied to arbitrary complex designs subsequently. A new key characteristic of our approach is that both transformation environment and transformation entry tool are based on a very compact definition of the hardware description language grammar in use, and both of them are fully automatically generated from that basic grammar definition. This makes our approach highly open for other hardw...