The history of luaTEX 2006–2009 / v 0.50 - Pragma ADE

table can contain information about the xml root document so that associated ltering
and handling can be reconstructed. With the section title we store information about the
preceding label text (seldom used, think of ‘Part B’).
This entry is used for lists as well as cross referencing. Actually, the stored information is
also used for markings (running heads). This means that these mechanisms must be able
to distinguish between where and how information is stored.
These tables look rather verbose and indeed they are. We end up with much larger multipass
data les but fortunately loading them is quite efcient. Serializing on the other
hand might cost some time which is compensated by the fact that we no longer store
information in token lists associated with nodes in TEX's lists and in the future we might
even move more data handling to the Lua end. Also, in future versions we will share
similar data (like page number information) more efciently.
Storing date at the Lua end also has consequences for the typesetting. When specic data
is needed a call to Lua is necessary. In the future we might offer both push and pull methods
(Lua pushing information to the typesetting code versus Lua triggering typesetting
code). For lists we pull, and for registers we currently push. Depending on our experiences
we might change these strategies.
A side effect of the rewrite is that we force more consistency. For instance, you see a conversion
eld in the list. This is the old way of dening the way a number gets converted.
The modern approach is to use sets. Because we now have a more stringent inheritance
model at the user interface level, this might lead to incompatible conversions at lower
levels (when unset). Instead of cooking up some nasty compatibility hacks, we accept
some incompatibility, if only because users have to adapt their styles to new font technology
anyway. And for older documents there is still MkII.
Instead of introducing many extra conguration variables (for each level of sectioning)
we introduce sets. These replace some of the existing parameters and are the follow up
on some (undocumented) precursor of sets. Examples of sets are:
\definestructureseparatorset [default][][.]
\definestructureconversionset[default][][numbers]
\definestructureresetset [default][][0]
\definestructureprefixset [default][section-2,section-3][]
\definestructureseparatorset [appendix][][.]
\definestructureconversionset[appendix][Romannumerals,Characters][]
\definestructureresetset [appendix][][0]
The third parameter is the default value. The sets that relate to typesetting can have a
rendering specication:
246 Everything structure