abr=!ie

The abr=!ie parameter tells the DFA ad servers not to serve JavaScript content if the browser is Internet Explorer. This parameter is included only in the Iframe/JavaScript combination tags, not in JavaScript tags without Iframes. According to HTML conventions, browsers are not supposed to read any content between tags. As such, any browser that recognizes Iframes should read only the DFA Iframe tags, not the JavaScript tags. However, some obsolete versions of Internet Explorer read both sets of tags. The abr=!ie parameter ensures that these browsers are served only one ad for each set of DFA ad tags. This parameter is included only in the Iframe/JavaScript combination tags, not in JavaScript tags without Iframes.

If you are using the correct and the complete Iframe tag provided by DFA, then abr=!ie would not cause any issue.