UML Templates allow to capture models whose some of their constituents are parameters. This construct is general enough to be used in many ways, such as generic class representation, Design Pattern modeling, view or aspect-oriented modeling (AOM). In this paper, we concentrate on this last usage and the specific characteristics of so called ''Aspectual Templates". Such templates can be applied to enrich existing models as far as they conform to a required model. Template parameters are exploited here to specify some required model, so that they must be constrained to form a full model structure. After recall of UML templates and their metamodel, we present the specificities of their aspectual interpretation, existing works and identify the issues. Then we show how standard UML templates can be enhanced to capture aspectual ones. For this, a specialization of the UML template metamodel is detailed and OCL constraints are formulated due to this specific interpretation and its proper mechanisms. As a result, this metamodel specialization is fully compatible with the existing one so that aspectual templates are full UML standard ones. Finally, we present an algorithm which constructs the result of the application of an Aspectual Template to a model. This algorithm also works for aspectual template to template application. Presented results were implemented and made available in the EMF (Eclipse Modeling Framework) technology.