Efficient evaluation of XML Query Languages has become a crucial issue for XML exchanges and integration. Tree Pattern (Sihem et al., 2002; Jagadish et al., 2001; Chen et al., 2003) are now well admitted for represen- ting XML Queries and a model -called TGV (Travers, 2006; Travers et al., 2006; Travers et al., 2007c)- has extended the Tree Pattern representation in order to make it more intuitive, respect full XQuery specification and got support to be manipulated, optimized and then evaluated. For optimization, a search strategy is needed. It consists in generating equivalent execution plan using exten- sible rules and estimate cost of plan to find the better one. We propose the specification of extensible rules that can be used in heterogeneous environment, supporting XML and manipulating Tree Patterns.