Level 'b' showed how you can copy articles by reference using the articles title as a substitution variable.  Well, the article will be shown in some permutation with articles from the other cats, and you can refer to the titles of those articles also!

Consider the following article body:

For many {$location} {$interfaith} couples, finding the right {$ceremony} center and {$location} {$ceremony} officiant can be more challenging than meeting the parents. Fortunately, New York City is full of {$ceremony} ministers and rabbis willing to unite all {$interfaith} couples. We are most willing to personalize the {$ceremony} according to your wishes, however unorthodox.

Rabbi Genn is a {$interfaith} NY & NM {$ceremony} Officiant, Interfaith Minister and {$location} Wedding Celebrant who performs spiritual ceremonies and weddings as well as non-denominational and interfaith {$ceremony} straight from the heart.

That text intermixes location, interfaith, and ceremony values and, when expanded, builds SEO phrases, not just a block of references to term1 followed by a block of references to term2 and then a block of references to term3.