For as long as I can recall, e-book readers have provided tools for bookmarking, highlighting, and annotation. But that didn't stop Microsoft from applying for (in 1999) and the US Patent and Trademark Office from granting (just recently) a patent for a
"Method and apparatus for capturing and rendering text annotations for non-modifiable electronic content". Non-modifiable content refers to content whose consistency is for various reasons not allowed to change. DRM-protected and copyrighted works come to mind.
The invention works like this:
- A user selects some kind of anchor object (which can be text or a graphic) in the document to locate where he wants an annotation to be placed.
- The software determines the file position in the document associated with the selected object.
- The user adds his annotation (which may include highlighting, textual notes, drawings, etc.) and, eventually, returns to reading the document.
- Meanwhile, the annotation is being stored along with the file position in a separate, linked file. Alternatively, the non-modifiable document may include a write-enabled portion with the annotations being added to it. The underlying document remains in an unmodified state.
If this doesn't blow your socks off, I cannot blame you. There is nothing new about this invention, nor does it require a particular technical understanding.
Mobipocket uses external "information storage" files (.mbp) to keep track of annotations (including bookmarks, notes, custom links, drawings, modifications, highlights).
Vade Mecum stores annotations and highlighting in separate files in the program's metadata folder. To name just two, and I am pretty sure other readers work similarly. Whoever granted this patent in the USPTO administration must have been smoking some bad granola at the time.