Watermarks can range greatly in terms of style and method of deployment.
Some watermarks are simple text with or without transparency.
Or you can use a graphic logo or a graphic logo with text.
A graphic can "look" like text , but from a authoring and software coding perspective is NOT text.
We are looking at the ability to import graphic files with and or with out transparency.
We are also looking at a text entry feature.
Below is just one example of a "watermark".
There are hundreds of examples of "watermarks"