% \iffalse meta-comment % % Copyright 2019-2020 % The LaTeX3 Project and any individual authors listed elsewhere % in this file. % % This file is part of the LaTeX base system. % ------------------------------------------- % % It may be distributed and/or modified under the % conditions of the LaTeX Project Public License, either version 1.3c % of this license or (at your option) any later version. % The latest version of this license is in % https://www.latex-project.org/lppl.txt % and version 1.3c or later is part of all distributions of LaTeX % version 2008 or later. % % This file has the LPPL maintenance status "maintained". % % The list of all files belonging to the LaTeX base distribution is % given in the file `manifest.txt'. See also `legal.txt' for additional % information. % % The list of derived (unpacked) files belonging to the distribution % and covered by LPPL is defined by the unpacking scripts (with % extension .ins) which are part of the distribution. % % \fi % Filename: ltnews31.tex % % This is issue 31 of LaTeX News. \NeedsTeXFormat{LaTeX2e}[2020-02-02] \documentclass{ltnews} \usepackage[T1]{fontenc} \usepackage{lmodern,url,hologo} \usepackage{csquotes} \usepackage{multicol} \providecommand\meta[1]{$\langle$\textit{#1}$\rangle$} \providecommand\option[1]{\texttt{#1}} \providecommand\env[1]{\texttt{#1}} \providecommand\XeTeX{\hologo{XeTeX}} \providecommand\LuaTeX{\hologo{LuaTeX}} \providecommand\pdfTeX{\hologo{pdfTeX}} \providecommand\MiKTeX{\hologo{MiKTeX}} \providecommand\CTAN{\textsc{ctan}} \providecommand\TL{\TeX\,Live} \providecommand\githubissue[2][]{\ifhmode\unskip\fi \quad\penalty500\strut\nobreak\hfill \mbox{\small\slshape(% \href{https://github.com/latex3/latex2e/issues/\getfirstgithubissue#2 \relax}% {github issue#1 #2}% )}% \par\smallskip} % simple solution right now (just link to the first issue if there are more) \def\getfirstgithubissue#1 #2\relax{#1} \providecommand\sxissue[1]{\ifhmode\unskip\fi \quad\penalty500\strut\nobreak\hfill \mbox{\small\slshape(\url{https://tex.stackexchange.com/#1})}\par} \providecommand\gnatsissue[2]{\ifhmode\unskip\fi \quad\penalty500\strut\nobreak\hfill \mbox{\small\slshape(% \href{https://www.latex-project.org/cgi-bin/ltxbugs2html?pr=#1\%2F#2}% {gnats issue #1/#2}% )}% \par} \let\cls\pkg \providecommand\env[1]{\texttt{#1}} \vbadness=1400 % accept slightly empty columns %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \iffalse % only for TUB production \usepackage{graphicx} \makeatletter % Xe\TeX{} requires reflecting the first E, hence we complain if the % graphics package is not present. (For plain documents, this can be % loaded via Eplain.) Also, at Barbara's suggestion, if the current % font is slanted, we rotate by 180 instead of reflecting so there is at % least a chance to look ok. (The magic values here seem more or less % ok for \texttt{cmsl} and \texttt{cmti}.) % % \begin{macrocode} \def\tubreflect#1{% \@ifundefined{reflectbox}{% \TBerror{A graphics package must be loaded for \string\XeTeX}% }{% \ifdim \fontdimen1\font>0pt \raise 1.6ex \hbox{\kern.1em\rotatebox{180}{#1}}\kern-.1em \else \reflectbox{#1}% \fi }% } \def\tubhideheight#1{\setbox0=\hbox{#1}\ht0=0pt \dp0=0pt \box0 } \def\XekernbeforeE{-.125em} \def\XekernafterE{-.1667em} \DeclareRobustCommand{\Xe}{\leavevmode \tubhideheight{\hbox{X% \setbox0=\hbox{\TeX}\setbox1=\hbox{E}% \ifdim \fontdimen1\font>0pt \def\XekernbeforeE{0em}\fi \lower\dp0\hbox{\raise\dp1\hbox{\kern\XekernbeforeE\tubreflect{E}}}% \kern\XekernafterE}}} \def\XeTeX{\Xe\TeX} \def\XeLaTeX{\Xe{\kern.11em \LaTeX}} \fi %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \publicationmonth{February} \publicationyear{2020} \publicationissue{31} \begin{document} %\addtolength\textheight{4.2pc} % only for TUB \maketitle {\hyphenpenalty=10000 \spaceskip=3.33pt \hbadness=10000 \tableofcontents} \setlength\rightskip{0pt plus 3em} \medskip %\section{Introduction} % %This document is under construction \ldots \section{Experiences with the \LaTeX\ \texttt{-dev} formats} As reported in the previous \emph{\LaTeX{} News}, we have made a pre-release version of the \LaTeX{} kernel available as \LaTeX\texttt{-dev}. Overall, the approach of having an explicit testing release has been positive: it is now readily available in \TeX{} systems and is getting real use\\ beyond the team. The current release has been tested by a number of people, and we have had valuable feedback on a range of the new ideas. This has allowed us to fix issues in several of the new features, as described below. We wish to thank all the dedicated users who have been trying out the development formats, and we encourage others to do so. Pre-testing in this way does mean that, for the vast majority of users, problems are solved before they even appear! \section{Concerning this release \ldots (Lua\LaTeX{} engine)} The new LuaHB\TeX{} engine is Lua\TeX{} with an embedded HarfBuzz library. HarfBuzz can be used by setting a suitable renderer in the font declaration. A basic interface for that is provided by \pkg{fontspec}. This additional font renderer will greatly improve the shaping of various scripts when using Lua\LaTeX{}, many of which are currently handled correctly only by \XeTeX{}, which always uses HarfBuzz. To simplify testing of the new engine, binaries have already been added to MiK\TeX{} and \TeX{}~Live 2019 and both distributions have already now changed the Lua\LaTeX-dev format to use it. Going forward, Lua\LaTeX\ (and Lua\LaTeX-dev) will both use the LuaHB\TeX{} engine. The timing of the switch to the LuaHB\TeX{} engine depends on the distribution you use (for \TeX{}~Live this will be with \TeX{}~Live 2020). \section{Improved load-times for \pkg{expl3}} The \LaTeX3 programming layer, \pkg{expl3}, has over the past decade moved from being largely experimental to broadly stable. It is now used in a significant number of third-party packages, most notably \pkg{xparse}, for defining interfaces in cases where no \pkg{expl3} code is \enquote{visible}. In addition, most \LaTeX{} documents compiled using \XeTeX{} or \LuaTeX{} load \pkg{fontspec}, which is written using \pkg{expl3}. The \pkg{expl3} layer contains a non-trivial number of macros, and when used with the \XeTeX{} and \LuaTeX{} engines, it also loads a large body of Unicode data. This means that even on a fast computer, there is a relatively large load time when using \pkg{expl3}. For this release, the team have made adjustments in the \LaTeXe{} kernel to pre-load a significant portion of \pkg{expl3} when the format is built. This is transparent to the user, other than the significant decrease in document processing time: there will be no \enquote{pause} whilst loading the Unicode data files. Loading \pkg{expl3} in documents and packages can continue to be done as usual; eventually, it will be possible to omit \begin{verbatim} \RequirePackage{expl3} \end{verbatim} entirely but, to support older formats, this is still recommended at present. \section[Improvements to \LaTeX{} font selection: NFSS] {Improvements to \LaTeX{}'s font selection\\ mechanism (NFSS)} \subsection{Extending the shape management in NFSS} Over time, more and more fonts have become available for use with \LaTeX{}. Many such font families offer additional shapes such as small caps italic (\texttt{scit}), small caps slanted (\texttt{scsl}) or swash (\texttt{sw}). By using \cs{fontshape} those shapes can be explicitly selected. For the swash shapes there is also \cs{swshape} and \cs{textsw} available. In the original font selection implementation a request to select a new shape always overrode the current shape. With the 2020 release of \LaTeX{} this has changed and \cs{fontshape} can now be used to combine small capitals with italic, slanted or swash letters, either by explicitly asking for \texttt{scit}, etc., or by asking for italics when typesetting already in small caps, and so forth. Using \cs{upshape} will still change italics or slanted back to an upright shape but will not any longer alter the small caps setting. To change small capitals back to upper/lower case you can now use \cs{ulcshape} (or \cs{textulc}) which in turn will not change the font with respect to italics, slanted or swash. % There is one exception: for compatibility reasons \cs{upshape} will change small capitals back to upright (\texttt{n} shape), if the current shape is \texttt{sc}. This is done so that something like \cs{scshape}\allowbreak\texttt{...}\allowbreak\cs{upshape} continues to work as before, but we suggest that you don't use that deprecated method in new documents. Finally, if you want to reset the shape back to normal you can use \cs{normalshape} which is a shorthand for \cs{upshape}\cs{ulcshape}. The way that shapes combine with each other is not hardwired; it is customizable and extensible if there is ever a need for this. The mappings are defined through \cs{DeclareFontShapeChangeRule} and the details for developers are documented in \texttt{source2e.pdf}. The ideas for this interface extension have been pioneered in \pkg{fontspec} by Will Robertson for Unicode engines, and in \pkg{fontaxes} by Andreas Bühmann and Michael Ummels for \pdfTeX{}; they are by now used in many font support packages. \subsection{Extending the font series management in NFSS} Many of the newer font families also come provided with additional weights (thin, semi-bold, ultra-bold, etc.)\ or several running widths, such as condensed or extra-condensed. In some cases the number of different values for series (weight plus width) is really impressive: for example, Noto Sans offers 36 fonts, from ultra-light extra condensed to ultra-bold medium width. Already in its original design, NFSS supported 9 weight levels, from ultra-light (\texttt{ul}) to ultra-bold (\texttt{ub}), and also 9 width levels, from ultra-condensed (\texttt{uc}) to ultra-expanded (\texttt{ux}): more than enough, even for a font family like Noto Sans. Unfortunately, some font support packages nevertheless invented their own names, so in recent years you have been able to find all kinds of non-standard series names (\texttt{k}, \texttt{i}, \texttt{j} and others), making it impossible to combine different fonts successfully using the standard NFSS mechanisms. Over the course of the last year a small number of individuals, notably, Bob Tennent, Michael Sharpe and Marc Penninga, have worked hard to bring this unsatisfactory situation back under control; so today we are happy to report that the internal font support files for more than a hundred font families are all back to following the standard NFSS conventions. Combining them is now again rather nice and easy, and from a technical perspective they can now be easily matched; but, of course, there is still the task of choosing combinations that visually work well together. In the original font selection implementation, a request to select a new series always overrode the current one. This was reasonable because there were nearly no fonts available that offered anything other than a medium or a bold series. Now that this has changed and families such as Noto Sans are available, combining weight and width into a single attribute is no longer appropriate. With the 2020 release of \LaTeX{}, the management of series therefore changed to allow independent settings of the weight and the width attributes of the series. For most users this change will be largely transparent as \LaTeX{} offers only \cs{textbf} or \cs{bfseries} to select a bolder face (and \cs{textmd} and \cs{mdseries} to return to a medium series): there is no high-level command for selecting a condensed face, etc. However, using the NFSS low-level interface it is now possible to ask for, say, \verb=\fontseries{c}\selectfont= to get a condensed face (suitable for a marginal note) and that would still allow the use of \cs{textbf} inside the note, which would select a bold-condensed face (and not a rather odd-looking bold-extended face in the middle of condensed type). The expectation is that this functionality will be used largely by class and package designers but, given that the low-level NFSS commands are usable on the document level and that they are not really difficult to apply, there are probably also a number of users who will enjoy using these new possibilities that bring \LaTeX{} back into the premier league for font usage. The ways in which the different series values combine with each other is not hardwired but is again customizable and extensible. The mappings are defined through \cs{DeclareFontSeriesChangeRule} and the details for developers are documented in \texttt{source2e.pdf}. \subsection{Font series defaults per document family} With additional weights and widths now being available in many font families, it is more likely that somebody will want to match, say, a medium weight serif family with a semi-light sans serif family, or that with one family one wants to use the bold-extended face when \cs{textbf} is used, while with another it should be bold (not extended) or semibold, etc. In the past this kind of extension was provided by Bob Tennent's \pkg{mweights} package, which has been used in many font support packages. With the 2020 release of \LaTeX{} this feature is now available out of the box. In addition we also offer a document-level interface to adjust the behavior of the high-level series commands \cs{textbf}, \cs{textmd}, and of their declaration forms \cs{bfseries} and \cs{mdseries}, so that they can have different effects for the serif, sans serif and typewriter families used in a document. For example, specifying \begin{verbatim} \DeclareFontSeriesDefault[rm]{bf}{sb} \DeclareFontSeriesDefault[tt]{md}{lc} \end{verbatim} in the document preamble would result in \cs{textbf} producing semi-bold (\texttt{sb}) when typesetting in a roman typeface. The second line says that the typewriter default face (i.e., the medium series \texttt{md}) should be a light-condensed face. The optional argument here can be either \texttt{rm}, \texttt{sf} or \texttt{tt} to indicate one of the three main font families in a document; if omitted you will change the overall document default instead. In the first mandatory argument you specify either \texttt{md} or \texttt{bf} and the second mandatory argument then gives the desired series value in NFSS nomenclature. \subsection{Handling of nested emphasis} In previous releases of \LaTeX{}, nested \cs{emph} commands automatically alternated between italics and upright. This mechanism has now been generalised so that you can now specify for arbitrary nesting levels how emphasis should be handled. The declaration \cs{DeclareEmphSequence} expects a comma separated list of font declarations corresponding to increasing levels of emphasis. For example, \begin{verbatim} \DeclareEmphSequence{\itshape,% \upshape\scshape,\itshape} \end{verbatim} uses italics for the first, small capitals for the second, and italic small capitals for the third level (provided you use a font that supports these shapes). If there are more nesting levels than provided, \LaTeX{} uses the declarations stored in \cs{emreset} (by default \cs{ulcshape}\cs{upshape}) for the next level and then restarts the list. The mechanism tries to be \enquote{smart} by verifying that the given declarations actually alter the current font. If not, it continues and tries the next level---the assumption being that there was already a manual font change in the document to the font that is now supposed to be used for emphasis. % Of course, this only works if the declarations in the list's entries actually change the font and not, for example, just the color. In such a scenario one has to add \cs{emforce} to the entry, which directs the mechanism to use the entry, even if the font attributes appear to be unchanged. \subsection{Providing font family substitutions} Given that \pdfTeX{} can only handle fonts with up to 256 glyphs, a single font encoding can only support a few languages. The \texttt{T1} encoding, for example, does support many Latin-based scripts, but if you want to write in Greek or Cyrillic then you will need to switch encodings to \texttt{LGR} or \texttt{T2A}. Given that not every font family offers glyphs in such encodings, you may end up with some default family (e.g., Computer Modern) that doesn’t blend in well with the chosen document font. For such cases NFSS now offers \cs{DeclareFontFamilySubstitution}, for example: \begin{verbatim} \DeclareFontFamilySubstitution{LGR} {Montserrat-LF}{IBMPlexSans-TLF} \end{verbatim} tells \LaTeX{} that if you are typesetting in the sans serif font \texttt{Montserrat-LF} and the Greek encoding \texttt{LGR} is asked for, then \LaTeX{} should use \texttt{IBMPlexSans-TLF} to fulfill the encoding request. The code is based on ideas from the \pkg{substitutefont} package by Günter Milde, but the implementation is different. \subsection{Providing all text companion symbols by default} The text companion encoding \texttt{TS1} was originally not available by default, but only when the \pkg{textcomp} package was loaded. The main reason for this was limited availability of fonts with this encoding other than Computer Modern; another was the memory restrictions back in the nineties. These days neither limitation remains, so with the 2020 release all the symbols provided with the \pkg{textcomp} package are available out of the box. Furthermore, an intelligent substitution mechanism has been implemented so that glyphs missing in some fonts are automatically substituted with default glyphs that are sans serif if you typeset in \cs{textsf} and monospaced if you typeset using \cs{texttt}. In the past they were always taken from Computer Modern Roman if substitution was necessary. \typeout{^^J^^J***************************************} \typeout{** This example needs LaTeX 2020-02-02} \typeout{** to come out correctly !!} \typeout{***************************************^^J^^J} \textsf{This is most noticeable with \cs{oldstylenums} which are now taken from \texttt{TS1} so that you no longer get \textrm{\oldstylenums{1234}} but \oldstylenums{1234} when typesetting in sans serif fonts}\texttt{ and \oldstylenums{1234} when using typewriter fonts.} If there ever is a need to use the original (inferior) definition, then that remains available as \cs{legacyoldstylenums}; and to fully revert to the old behavior there is also \cs{UseLegacyTextSymbols}. The latter declaration reverts \cs{oldstylenums} and also changes the footnote symbols, such as \cs{textdagger}, \cs{textparagraph}, etc., to pick up their glyphs from the math fonts instead of the current text font (this means they always keep the same shape and do not nicely blend in with the text font). With the text companion symbols as part of the kernel, it is normally no longer necessary to load the \pkg{textcomp} package, but for backwards compatibility this package will remain available. There is, however, one use case where it remains useful: if you load the package with the option \texttt{error} or \texttt{warn} then substitutions will change their behavior and result in a \LaTeX{} error or a \LaTeX{} warning (on the terminal), respectively. Without the package the substitution information only appears in the \texttt{.log} file. If you use the option \texttt{quiet}, then even the information in the transcript is suppressed (which is not really recommended). \subsection{New \texttt{alias} size function for use in \texttt{.fd} files} % These are really called ``size functions'' in NFSS, a bit weird I know Most of the newer fonts supported in \TeX{} have been set up with the \texttt{autoinst} tool by Marc Penninga. In the past, this program set up each font using the face name chosen by that font's designer, e.g., \enquote{\texttt{regular}}, \enquote{\texttt{bold}}, etc. These face names were then mapped by substitution to the standard NFSS series names, i.e., \enquote{\texttt{m}} or \enquote{\texttt{b}}. As a result one got unnecessary substitution warnings such as \enquote{\texttt{Font T1/abc/bold/n not found, using T1/abc/b/n instead}}. %FMi the message above is actually different and longer but ... We now provide a new NFSS size function, \texttt{alias}, that can and will be used by \texttt{autoinst} in the future. It provides the same functionality as the \texttt{subst} function but is less vocal about its actions, so that only significant font substitutions show up as warnings. \subsection{Suppress unnecessary font substitution warnings} Many sans serif fonts do not have real italics but usually only oblique/slanted shapes, so the substitution of slanted for italics is natural and in fact many designers talk about italic sans serif faces even if in reality they are oblique. With nearly all sans serif font families, the \LaTeX{} support files therefore silently substitute slanted if you ask for \cs{itshape} or \cs{textit}. This is also true for Computer Modern in \texttt{T1} encoding but in \texttt{OT1} you got a warning on the terminal even though there is nothing you can do about it. This has now been changed to an information message only, written to the \texttt{.log} file. % \githubissue{172} \vspace{-\smallskipamount} \pagebreak \section{Other changes to the \LaTeX{} kernel} \subsection{UTF-8 characters in package descriptions} In 2018 we made UTF-8 the default input encoding for \LaTeX{} but we overlooked the case of non-ASCII characters in the short package descriptions used in declarations, e.g., in the optional argument to \cs{ProvidesPackage}. They worked (sometimes) before, but the switch to UTF-8 made them always generate an error. This has been corrected. % \githubissue{52} \subsection[Fix inconsistent hook setting when\texorpdfstring{\\}{} loading packages]% {Fix inconsistent hook setting when loading packages} As part of loading a package, the command \texttt{\textbackslash}\textit{package}\texttt{.sty-h@@k} gets defined. However, attempting to load a package a second time resulted in this hook becoming undefined again. Now the hook remains defined so that extra loading attempts do not change the state of \LaTeX{} (relevant only to package developers). % \githubissue{198} \subsection{Avoid spurious warning if \texttt{LY1} is made the default encoding} Making \texttt{LY1} the default encoding, as is done by some font support packages, gave a spurious warning even if \cs{rmdefault} was changed first. This was corrected. % \githubissue{199} \enlargethispage{-\smallskipamount} \vspace{-\medskipamount} \subsection{Ensure that \cs{\textbackslash} remains robust} In the last release we made most document-level commands robust, but \cs{\textbackslash} became fragile again\\ whenever \cs{raggedright} or similar typesetting\\ was used. This has been fixed. % \githubissue{203} \subsection{Make math delimiters robust in a different way} Making math delimiters robust caused an issue in some situations. This has been corrected. This also involved a correction to \pkg{amsmath}. % \githubissue{251} \subsection{Allow more write streams with \texttt{filecontents} in \LuaTeX} Most \TeX{} engines only support a maximum of sixteen concurrently open write streams, and when those have been used up, then \texttt{filecontents} or any other code trying to open one will fail. In \LuaTeX{} more write streams are available and those can also now be utilised. % \githubissue{238} \subsection{Allow spaces in \texttt{filecontents} option list} Leaving spaces or newlines in the option list prevented the options from being correctly recognized. This\\ has been corrected. % \githubissue{256} \subsection{New \texttt{reverselist} Lua callback type} A new callback type, \texttt{reverselist}, was added:\\ \texttt{post\_mlist\_to\_hlist\_filter} and \texttt{post\_linebreak\_filter} are now of this type. \section{Changes to packages in the \pkg{graphics} category} \subsection[Make \pkg{color}/\pkg{graphics} user-level commands robust] {Make \pkg{color} \& \pkg{graphics} user-level commands robust} Some of the user-level commands in \pkg{color}, \pkg{graphics} and \pkg{graphicx}, %\pagebreak such as \cs{textcolor} or \cs{includegraphics}, were still fragile so didn't work in moving arguments.\\ All of these are now robust. % \githubissue{208} \section{Changes to packages in the \pkg{tools} category} \subsection{Fixed column depth in boxed \texttt{multicols}} The \texttt{multicols} environment was setting \cs{maxdepth} when splitting boxes; but, due to the way the internal interfaces of \LaTeX{} are designed, it should have used \cs{@maxdepth} instead. As a result, balanced boxed multicols sometimes ended up having different heights even if they had exactly the same content. % \githubissue{190} \subsection{Ensure that \texttt{multicols} does not lose text} The \texttt{multicols} environment needs a set of consecutively numbered boxes to collect column material. The way those got allocated could result in disaster if other packages allocated most boxes below box~255 (which \TeX{} always uses for the output page). In the original implementation that problem was avoided because one could only allocate box numbers below~255, but nowadays the \LaTeX{} allocation routine allows allocating box numbers both below and above~255. So the assumption that when asking for, say, 20~boxes you always get a consecutive sequence of~20 box register numbers became no longer true: some of the column material could end up in box~255, where it would get overwritten. This has now been corrected by allocating all necessary boxes with numbers above~255 whenever there aren't enough lower-numbered registers available. % \githubissue{237} \subsection{Allow spaces in \cs{hhline} arguments} The \verb|\hhline| command, which allows the specification of rule segments in \texttt{tabular} environments, now allows (but ignores) spaces between its tokens: so \verb|\hhline{: = : =}| is now allowed and is equivalent to \verb|\hhline{:=:=}|. This matches similar token arguments in \LaTeX{} such as the \verb|[h t p]| argument on floats. A similar change has been made to the extended \verb|\hhline| command in the \texttt{colortbl} package. % \githubissue{242} \section{\LaTeX{} requirements on engine primitives} Since the finalization of \eTeX{} in 1999, a number of additional `utility' primitives have been added to \pdfTeX{}. Several of these are broadly useful and have been required by \pkg{expl3} for some time, most notably \cs{pdfstrcmp}. Over time, a common set of these `post-\eTeX{}' primitives have been incorporated into \XeTeX{} and (u)p-\TeX{}; they were already available in \LuaTeX{}. A number of these additional primitives are needed to support new or improved functionality in \LaTeX{}. This is seen for example in the improved UTF-8 handling, which uses \cs{ifincsname}. The following primitive functionality (which in \LuaTeX{} may be achieved using Lua code) will therefore be \emph{required} by the \LaTeX{} kernel and core\\ packages from the start of 2021: % \begingroup\setlength\columnsep{0pt} \begin{multicols}{2} \fontsize{9.3}{11.3}\selectfont \begin{itemize} \item \cs{expanded} \item \cs{ifincsname} \item \cs{ifpdfprimitive} \item \cs{pdfcreationdate} \item \cs{pdfelapsedtime} \item \cs{pdffiledump} \item \cs{pdffilemoddate} \item \cs{pdffilesize} \item \cs{pdflastxpos} \item \cs{pdflastypos} \item \cs{pdfmdfivesum} \item \cs{pdfnormaldeviate} \item \cs{pdfpageheight} \item \cs{pdfpagewidth} %\end{itemize} %\end{multicols} % % very manual! multicol needs update to detect that it is used % inside twocolumn! % %\begin{multicols}{2} %\begin{itemize} \item \cs{pdfprimitive} \item \cs{pdfrandomseed} \item \cs{pdfresettimer} \item \cs{pdfsavepos} \item \cs{pdfsetrandomseed} \item \cs{pdfshellescape} \item \cs{pdfstrcmp} \item \cs{pdfuniformdeviate} \end{itemize} \end{multicols} \endgroup For ease of reference, these primitives will be referred to as the `\pdfTeX{} utilities'. With the exception of \cs{expanded}, these have been present in \pdfTeX{} since the release of version 1.40.0 in 2007; \cs{expanded} was added for \TeX{}~Live 2019. Similarly, the full set of these utility primitives has been available in \XeTeX{} from the 2019 \TeX{}~Live release, and has always been available in \LuaTeX{} (some by Lua emulation). % The Japanese p\TeX{} and up\TeX{} gained all of the above (except \cs{ifincsname}) for \TeX{}~Live 2019 and will both have that primitive also from the 2020 release onward. At the same time, engines which are fully Unicode-capable must provide the following three primitives: \vspace{-\smallskipamount} \begingroup\setlength\columnsep{0pt} \begin{multicols}{2} \fontsize{9.3}{11.3}\selectfont \begin{itemize} \item \cs{Uchar} \quad \textbullet{}\hspace{\labelsep}\cs{Ucharcat} \item \cs{Umathcode} \end{itemize} \end{multicols} \vspace{-\smallskipamount} \endgroup % Note that it has become standard practice to check for Unicode-aware engines by using the existence of the \cs{Umathcode} primitive. As such, this is already a requirement: engines lacking these primitives cannot use Unicode features of the \LaTeXe{} kernel or \pkg{expl3}. Note also that up\TeX{} can handling Unicode but it is not classed as a Unicode engine by the base \LaTeX\ code. \enlargethispage*{\baselineskip} \vspace{3.9pt} % manual adjustment to align the bottom \begin{thebibliography}{9} \fontsize{9.3}{11.3}\selectfont \bibitem{31:devformat} Frank Mittelbach: \emph{The \LaTeX{} release workflow and the \LaTeX{} dev formats}. In: TUGboat, 40\#2, 2019. \url{https://latex-project.org/publications/} \bibitem{31:fntguide} \LaTeX{} Project Team: \emph{\LaTeXe{} font selection}.\\ \url{https://latex-project.org/help/documentation/fntguide.pdf} \bibitem{31:site-doc} \emph{\LaTeX{} documentation on the \LaTeX{} Project Website}.\\ \url{https://latex-project.org/help/documentation/} \end{thebibliography} \end{document}