In some embodiments, a method is provided for determining a localized region of overlap of first and second features from respective first and second conductive layers, and determining which enclosure rules to apply to vias formed between the first and second features. In a further aspect of the invention, a method may be provided to determine whether to apply symmetric or asymmetric via metal enclosure rules to a feature as a function of the local environment of the feature. In another aspect of the invention, a computer program product is provided to encode instructions for performing such a process.