All at once it makes sense.  Or at least I think it does... 

Thanks to Kevin Lindsey for his explanations about vector graphics and SVG.  He has really peaked my interest!

I was stuck in the world of bitmaps each time I thought about "ink".  I couldn't imagine storing all these ink objects in their raw form until I read a little about SVG and realized that you only need a set of points, plus some information about those points, to form an ink object.  Forget anything that is not part of the line.  Unlike bitmaps, the negative space is implied.  In fact, the negative space is most of the screen. 

Tablet pc's sample at a rate of 130 "pen events" -- units of motion that correspond to data points -- per second.   As you drag your pen or mouse across the screen, the position of your cursor is recorded every specified instant in time.  These points will have the jaggedness normally associated with digital drawing but this jaggednes can be smoothed out to better represent the intended curve or line.  Then, rather than just connecting the dots, a curve can be generated that closely matches the dot path.  This information may be smaller that the actual dots recorded and is definitely smaller that a bitmap of equivalent size.  Now this can be converted to text or shapes or whatever you want... 

A great reource on SVG and vector graphics algorithms.   http://www.kevlindev.com/blog/weblog.php

Now that I think I know what ink is, something occurs to me.  Handwriting is an ancient form of identification that has carried over into the digital age.  We are still expected to hand-sign many documents to verify their authenticity and authority.  I have been annoyed at this requirement many times, particularly when I sign "fat guy" rather than my name and it matters not.  Why make me sign it at all?  Many trqansactions have been restricted from electronic fulfillment because they require a physical signature.  Ink is going to be a record of a person's handwriting.  It will now be possible to copy a person's handwriting in its raw form as a set of digital ink.  Since ink is vector based, it will not be necesary to find each letter but rather draw out a document in that person's handwriting based on their ink records.  This is not a bad thing, I think, because it will remove the false perception that handwriting is a personally unique, identifiable tool.  Handwriting should be a way to record ideas and experiences.  Authentication and authorization should require something a little more modern