As a general approach to procedural mesh definition we propose two mechanisms for mesh modification: generalized subdivision and rule based mesh growing. In standard subdivision, a specific subdivision rule is applied to a mesh to get a succession of meshes converging to a limit surface. A generalized approach allows different subdivision rules a each level of the subdivision process. By limiting he variations introduced at each level, convergence can be ensured; however in a number of cases it may be of advantage to exploit the expressivity of different subdivision steps a each level, without imposing any limits. Rule based mesh growing is an extension of L-systems to no only work on symbols, but connected symbols, representing faces in a mesh. This mechanism allows he controlled introduction of more complex geometry in places where it is needed to model fine details. Using both these mechanisms in combination we demonstrate, hat a great variety of complex objects can be easily modeled and compactly represented.