Re: length-spec vs. length for characteristics

[James Clark <jjc@xxxxxxxxxx>]

At 11:15 17/04/97 -0400, Paul Prescod wrote:

>How major are the changes to DSSSL going to have to
>be to allow us to work online where flow object sizes (e.g. page width)
>are not known until runtime?

The whole point of length-specs is that they allow the user to express
characteristic values in terms of quantities such as page-width that are not
known to the DSSSL engine.  This works because the set of operations that
are allowed on length-specs is limited.  Normal length-specs (not in tables)
can always be reduced to the form:

q + r*d

where q is a length, r is a float and d is the display-size.  For a
length-spec valued characteristic Jade will pass q and r to the backend.

James