X-Git-Url: http://mj.ucw.cz/gitweb/?a=blobdiff_plain;f=ucwmac.tex;h=6c7a5dec709091f01ec3e7ebf9c0ff9b65bfe290;hb=9d61b4ef87dbbff2ff43f6b6af3b7299e496f0e7;hp=87c0b4608ac2cbc83a85d371aa5e06992f2f44bf;hpb=f858ee391f0a68981e4a5e5a88411966b73c60e6;p=ucwmac.git

diff --git a/ucwmac.tex b/ucwmac.tex
index 87c0b46..6c7a5de 100644
--- a/ucwmac.tex
+++ b/ucwmac.tex
@@ -231,12 +231,17 @@
 \newbox\itembox
 \newcount\itemcount
 
+% Penalties (changed at compatibility level 1)
+\newcount\preitemizepenalty	\preitemizepenalty=0
+\newcount\postitemizepenalty	\postitemizepenalty=0
+
 \def\preitemize{
 	\ifitems
 		\vskip\prenesteditemizeskip
 		\advance\leftskip by \nesteditemindent
 		\advance\rightskip by \nesteditemnarrow
 	\else
+		\ifnum\preitemizepenalty=0\else\penalty\preitemizepenalty\fi
 		\vskip\preitemizeskip
 		\advance\leftskip by \itemindent
 		\advance\rightskip by \itemnarrow
@@ -248,6 +253,7 @@
 	\ifitems
 		\vskip\postnesteditemizeskip
 	\else
+		\ifnum\postitemizepenalty=0\else\penalty\postitemizepenalty\fi
 		\vskip\postitemizeskip
 	\fi
 }
@@ -357,6 +363,27 @@
 	\expandafter\let\csname ucwmod:#1\endcsname=\relax
 }
 
+% Compatibility levels
+% We try to be backwards compatible as much as we can, so all changes in behavior
+% (except for addition of new control sequences) are versioned. By default, ucwmac
+% starts in compatibility level 0, which should produce the same results as historic
+% versions of ucwmac. Use \ucwcompat{level} to upgrade to a given level, or if you
+% do not care about compatibility, \ucwcompat\ucwmaxcompat.
+
+\chardef\ucwcurrentcompat=0	% Currently active compatibility level
+\chardef\ucwmaxcompat=1		% Maximum supported compatibility level
+
+\def\ucwcompat#1{
+	\ucwcurrentcompat=#1
+	\ifcase #1
+		% Level 0 (default): old ucwmac
+	\or	% Level 1
+		\preitemizepenalty=-500
+		\postitemizepenalty=-500
+	\else\errmessage{Unsupported compatibility level #1 requested.}
+	\fi
+}
+
 %%% Epilog %%%
 
 % Let's hide all internal macros