Here's how I'd implement exact anchors using my second suggestion, a new
function code (0x9A) that sets the offset of the anchor's target within a
paragraph. The patch is completely untested--the code compiles, though--and
I'm not going to test it unless I get approval in principle for this
extension to the format.
Specifically, here is the proposed extension to the format.
New function:
0x00 0x9A byte1 byte2 (DoSetTargetByteOffset)
This function MUST follow right after a 0x00 0x0C b1 b2 b3 b4
(DoNamedAnchor) function, and it sets the byte offset of the anchor's target
within the target paragraph to 256*byte1 + byte2. If a
DoSetTargetByteOffset function is not given in the scope of a DoNamedAnchor
... DoAnchorEnd, the target byte offset is set to zero. A file that
has a DoSetTargetByteOffset function anywhere else than right after a
DoNamedAnchor will produce undefined behavior (just as currently, say, a
DoAnchorEnd by itself produces undefined behavior).
Backwards compatibility:
Older viewers should ignore any instances of a DoSetTargetByteOffset and
go to the beginning of the target paragraph, just as before. Therefore,
texts in the new format will be backwards compatible, except that the new
viewer feature of seeking to a precise position from link will not be
available.
Expectation from viewer:
Conforming viewers will align the link's target with the top of the
display
unless display options make this impossible (e.g., text on last
screenful),
or else will try to make the link's target conspicuous in some other
consistent
way. It is to be guaranteed, in any case, that any text right after the
target byte
be displayed on the screen.
--
Dr. Alexander R. Pruss
Department of Philosophy
Georgetown University
Washington, DC 20057-1133 U.S.A.
e-mail: [EMAIL PROTECTED]
online papers and home page: www.georgetown.edu/faculty/ap85
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"Philosophiam discimus non ut tantum sciamus, sed ut boni efficiamur."
- Paul of Worczyn (1424)
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