Wherever a template-reference can occur, more than one template-reference can occur

[kwatsen]

Requirements

This requirement enables configuration through composition. That is, that the total configuration for some node (and its descendants) may come from more than one template.

For example, assuming YANG for data model for 3-D graphics may require all objects to have a color, material, and a texture defined, but the data model did not define an ability for the color/material/texture to be referenced (i.e., no leafref). It would become tedious to explicitly set the same color/texture/material on many objects, and hence may be desirable to have a template to define a color, a template to define a texture, and a template to define a material, and to have the many objects refer to one of each kind of template to get their final configuration.

Non-Requirements

Implicit in this requirement is a need to define a rule for how overlaps/collisions are handled. For instance, the templates could be ordered or prioritized, with a "last-one wins" approach. Alternately, if the overlap/collision regards a list, it could be that the lists are merged. In any case, this requirement does NOT pick what approach may be used, leaving that decision to be made elsewhere.