UML Templates allow to capture reusable models through parameterization. The construct is general enough to be used in many ways, ranging from the representation of generic components (such as Java generics or C++ templates) to aspectual usage, including pattern-, aspect- and view-oriented modeling. We concentrate on this last usage and so-called aspectual templates which require that parameters must form a model of systems in which to inject new functionalities. Starting from this strict constraint, we derive an in-depth semantic enhancement of the standard. It is formalized as a fully UML-compliant interpretation in OCL of the template construct and its binding mechanism. In particular, this aspectual interpretation must be ensured in case of partial binding (not all parameters are valued). Partial binding of UML is a powerful technique which allows to obtain richer templates from the composition of other ones. As a major result, the present semantic enhancement is consistent with this capacity so that partial binding of aspectual templates produces aspectual templates. Finally, at an operational level, an algorithm for aspectual template (partial) binding operation is formulated and consequent reusable technology made available in EMF (Eclipse Modeling Framework) is presented.