We use text features such as textual delimiters, keywords, constants or text patterns, which we call anchors, to identify data regions on a web page. Using these anchors, we create patterns for [the] data regions and match them in a mixed bottom-up and top-down manner.
The first sentence speaks about data regions in general. Could ti be in the case of the second sentence? or I'd better to use "the" to say these data regions are the same data regions we pointed in the previous sentence?
Using the with the second "data regions" really only implies a specific group of data regions, not necessarily the ones you refers to at first.
Of course, it could be implied depending on how the example is understood.
To be clear, I would use those to clarify the relationship.
We use text features such as textual delimiters, keywords, constants or text patterns, which we call anchors, to identify data regions on a web page. Using these anchors, we create patterns for those data regions and match them in a mixed bottom-up and top-down manner.
