Document Link (DRL) Parameters - Supported?

We are running our Managed Documents in Webtop 6.7 – Build 6.7.2180.0204 SP2 15 Sept 2014.

Most are in MS Word format.

For each, we create a PDF rendition by means of Tools --> Transform --> PDF Rendition.

Then we create a hyperlink to the document object by using Right-click --> Email as link.

In order to always open the latest version, we append this switch onto the end of the hyperlink: /versionlabel/current

In order to ensure users only get a PDF version, we also append this switch to the hyperlink: /format/pdf

So the full hyperlink will look like this: http://io1documents/webtop/drl/objectId/0093c41e81ea7a57/versionlabel/current/format/pdf

Our original information came from here: https://dmcool.wordpress.com/category/webtop/

It is also mentioned here: https://community.emc.com/thread/127336?tstart=0

And here: https://community.emc.com/message/754683#754683

These hyperlinks are embedded in MANY other documents, so we need to do it this way to remove the need to update all the embedded links every time a document is updated.

This was implemented over a year ago and has been working fine until some weeks ago, when the system started ignoring the PDF request and simply opens the Word file.

My question is: Is the use of these switches a supported feature, and if so, what can we look for to fix it?