A proof-carrying code infrastructure can ensure safety of global computers. Such an infrastructure requires sound and complete semantics of the global computing platform. Bicolano is an operational semantics of the major part of the Java bytecode language. We present here two extension frameworks for the semantics and discuss their different features. Both frameworks are made in a modular fashion. The first one, so called horizontal, allows to extend states with additional information that traces a running program behaviour (e.g. memory consumption). The second one, so called vertical, additionally allows an extension to supplement the behaviour specified in the original semantics. A comparison of these frameworks is presented. In particular, we prove that the horizontal framework can be simulated by the vertical one and show an example of an extension which cannot be realised in the horizontal one, but can be realised in the vertical one. However, extensions in the horizontal framework are less memory consuming and conceptually simpler. In this light, the choice of the framework to use should depend on a particular application.