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I have come across quite a number of TeX internal parameters, like \clubpenalty, \widowpenalty, \abovedisplayshortskip and so on. Could you provide me with a complete list of them, what they are for and their default values?

Edit: As David Carlisle suggested, for penalties I find everything at this link. As for the others, many defaults are missing from both given references. I will make a list below of those explained in the tug list. If you feel I'm missing any parameter, please let me know. The question therefore becomes: what are the defaults of the following parameters?

  • \abovedisplayshortskip, the non-short equivalent, and the below equivalents of both;
  • \badness; is this set to a starting value or is this set the first time with the first box?
  • \baselineskip, \prevdepth (is this set to a starting value or not?), \lineskiplimit, \lineskip;
  • \boxmaxdepth and \maxdepth, here together since they are often the same value; in fact, in the tug list it is said, under \pagedepth, that \maxdepth in plain is 4pt;
  • \leaders, \cleaders and \xleaders;
  • What is the starting value of \deadcycles? Is it 0?
  • \defaulthyphenchar is a hyphen (-) by default, right?
  • \defaultskewchar; what is the \skewchar?
  • \delimiterfactor and \delimitershortfall;
  • \displayindent;
  • \displaywidth; this is normally \hsize, but what is \hsize by default?
  • \emergencystretch, \pretolerance and \tolerance;
  • \endlinechar;
  • \errorcontextlines;
  • \escapechar;
  • \hangafter, \hangindent;
  • \hbadness, \hfuzz;
  • \holdinginserts;
  • \inputlineno starts as 0, I should think;
  • Same goes for \insertpenalties;
  • What is the default (starting value) of \interlinepenalty?
  • \lefthyphenmin;
  • \mag;
  • \mathsurround;
  • \maxdeadcycles;
  • \medmuskip, \thinmuskip and \thickmuskip;
  • \nonscript;
  • \outputpenalty seems to be missing in the penalty link;
  • \overfullrule;
  • I'd guess \pagedepth starts out as 0pt;
  • Same goes for \pagefilstretch, \pagefillstretch and \pagefilllstretch;
  • Same goes for \pageshrink and \pagestretch, and \pagegoal is completely dealt with on the tug list;
  • Same as \pageshrink goes for \pagetotal;
  • \parfillskip and \parskip;
  • \parindent;
  • \pausing;
  • What is the starting value of \predisplaysize?
  • Same question about \pretolerance, \tolerance and \prevdepth;
  • And about \prevgraph;
  • What is the default for \righthyphenmin?
  • And for \rightskip and \leftskip?
  • And for \scriptspace?
  • What are \spacefactor, \spaceskip and \xspaceskip, and their default values?
  • What are \splittopmark, \topmark and \splitfirstmark's defaults?
  • What are \splitmaxdepth and \splittopskip?
  • What's the default for \tabskip?
  • For completeness, I list \time, though this requires no explanation;
  • Default for \topskip?
  • And \tracingcommands and \tracinglostcommands and mates (-macros, -online, -output, -pages, -paragraphs, -restores, -stats)?
  • And for \vbadness, \vfuzz and \voffset and \vsize?

If you feel this is still too broad, answer only about the dimen parameters, and notify me. I'll ask separate questions for the rest.

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MickG
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    texdoc texbytopic? – Torbjørn T. Sep 28 '14 at 21:15
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    The TeXbook is the best reference but there's a list of primitives at http://www.tug.org/utilities/plain/cseq.html – Nicola Talbot Sep 28 '14 at 21:21
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    This occupies a large part of the TeXbook; an answer would require much more than the allotted space. And several hours' work. – egreg Sep 28 '14 at 21:37
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    Most of the ones you mention are penalties, for which a full list is here http://tex.stackexchange.com/questions/51263/what-are-penalties-and-which-ones-are-defined/51264#51264 – David Carlisle Sep 28 '14 at 23:25
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    Only @egreg could say that it would take mere hours to properly document all of TeX's internal parameters... – cfr Sep 29 '14 at 01:43
  • Everyone please see the edit. – MickG Sep 29 '14 at 17:56
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    @MickG Well, I reviewed the question and I voted to leave it closed. I'll try to explain why. It still is too broad, and it doesn't make any sense to explain here how all the internals work. There are books that aim at doing this, but they are couple hundred pages long, and not couple paragraphs. Three good things were already suggested: Read TeX by Topic, read The TeXbook or open the primitives reference at tug.org. Since basically only such links can stand as answers, the question doesn't fit in the Q&A format of StackExchange. – yo' Sep 29 '14 at 18:46
  • I also reviewed and agree with @tohecz. If you do not have access to a print copy of The TeXbook you can always review its source. – Paul Gessler Sep 29 '14 at 19:00
  • @tohecz I don't want to know how they work. I want to k.ow their starting values only, except in very few cases. And if that is still too broad, we make this question only about \dimen params and leave the rest to separate questions. Is telling me what the defaults for the params of that class are and what a few of them are for still too broad? – MickG Sep 29 '14 at 19:01
  • And I plan to read TeX by topic - I've already opened it and am waiting for spare time to read it, which in the régime of a 6-course Uni semester surely doesn't about :). – MickG Sep 29 '14 at 19:03
  • If I managed to list those params, a "table" with their defaults should fit in an answer, right? Then a few paragraphs (2 at most, I should think) are enough to explain the functioning of the 8 parameters I asked the functioning of, and we're done. What's so terribly long about that? – MickG Sep 29 '14 at 19:06
  • @MickG "default" in which context? many classes re-define a good portion of them. And btw, you can get the value of any of them using \the\whateverparameterdimenandsuchhere. – yo' Sep 29 '14 at 19:12
  • Let's say we gloss "default" with "starting values in plain, plus notes as to redefinitions in LaTeX or classes, without new values". What about that @tohecz? – MickG Sep 29 '14 at 19:25
  • That would mean the core of the "defaults" part would be a copy-pasted chunk of plain.tex, about a hundred lines, plus the redefinition notes. Also, I see some values are in commented lines, so an explanation would be required as to the reason for commenting those lines out. – MickG Sep 29 '14 at 19:27
  • Several of those parameters don't have an “initial” value (\prevdepth, \badness, \holdinginserts and \...mark are just a few instances) because they frequently change their value at runtime. Others are expected to be set by a format (in LaTeX it would be a class), among them all the \...skip. Others have quite predictable defaults (\escapechar and \defaulthyphenchar among them). Some are quite arcane (\pausing and \uchyph). – egreg Sep 29 '14 at 22:01
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    @MickG See http://tex.stackexchange.com/questions/38674/the-the-command/38680#38680 for how to access the parameters' value. – egreg Sep 29 '14 at 22:07
  • @egreg I guess your next-to-last comment, with complete lists of the various categories you mentioned, would do fine as an answer :). Anyway, if this question gets closed, will it end up deleted eventually? – MickG Sep 30 '14 at 19:52
  • My comment was just to show a few problems related to answering the question. Knowing that some parameters have default values and others don't is not very useful, is it? – egreg Sep 30 '14 at 20:01
  • Well @egreg, it tells me the list of defaults is cut down, and would tell me where to look for the initialization of other parameters (those set by a format - report in my case). For the rest, there are default values. Many parameters have an explanation of how they are changed on the tug list, and if one adds they have no defaults, I'm satisfied. If I ask "What is the default for \x?", the answer may well be "\x has no default", couldn't it :)? – MickG Sep 30 '14 at 20:11

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