I have seen tags like this in HTML. What are these attributes?

**This is NOT a duplicate of the `data-*` question.**

**Edit:**
I am looking for these two specific attributes, not `data-*` in general, nor data-require**d**, as Google suggests. If you search the web, you can find these attributes are used in many places. I guess this is some like of dependency management software? 

    &lt;link data-require=&quot;bootstrap-css@*&quot; data-semver=&quot;3.0.0&quot; rel=&quot;stylesheet&quot; href=&quot;//netdna.bootstrapcdn.com/bootstrap/3.0.0/css/bootstrap.min.css&quot; /&gt;
     
    &lt;script data-require=&quot;angular.js@1.1.x&quot; src=&quot;https://ajax.googleapis.com/ajax/libs/angularjs/1.1.5/angular.js&quot; data-semver=&quot;1.1.5&quot;&gt;&lt;/script&gt;
    &lt;script data-require=&quot;ui-bootstrap@0.5.0&quot; data-semver=&quot;0.5.0&quot; src=&quot;http://angular-ui.github.io/bootstrap/ui-bootstrap-tpls-0.6.0.js&quot;&gt;&lt;/script&gt;


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What are "data-require" "data-semver" in HTML files?