Drilling for Translatable Content

I’ve been spending a lot of time with XML content recently.

In one case I received content where there are XML elements which have translatable attributes. Within this translatable attribute text are custom placeholder tags which in turn have translatable attributes.

<cust-ele att="needs-translation" value="Here is text with [proprietary att='I also require translation' dnt="77yf990"] placeholders contained within."/>

Borrowing from XLIFF, my current approach is to markup like so:

<cust-ele att="needs-translation" value=""><trans-att id="765fe3">Here is text with <ph id="432ab">[proprietary att='<sub>I also require translation</sub> dnt="77yf990"]</ph> placeholders contained within.</trans-att></cust-ele>

Is anyone else seeing this madness?