John Matonis defines ecash as portable if:

	The security and use of the digital cash is not
	dependent on any physical location.  The cash
	can be transferred through computer networks and
	off the computer network into other storage

In their test stages, none of the ecash I experimented with
was transferrable to any other denomination or off my computer.

The ecash system Matonis would probably recommend would 
incorporte ecash with cash cards and cash card readers so that
a user could transfer cash from card to computer and vice versa.

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