morrell@hpsal2.HP.COM (Michael Morrell) (10/12/88)
Does anyone know the exact definition of "point" (as in a 12-point font)? Some references (most nroff manuals) say there are 72 points to the inch, but others simply say (including my Webster's!!!) that a point is "nearly" equal to 1/72 of an inch. Who is right? Michael
anderson@vms.macc.wisc.edu (Jess Anderson, MACC) (10/13/88)
In article <2610015@hpsal2.HP.COM>, morrell@hpsal2.HP.COM (Michael Morrell) writes... ]Does anyone know the exact definition of "point" (as in a 12-point font)? ]Some references (most nroff manuals) say there are 72 points to the inch, ]but others simply say (including my Webster's!!!) that a point is "nearly" ]equal to 1/72 of an inch. Who is right? 1 point = 0.01384 inch. ==Jess Anderson======(home:)========INTERNET: anderson@vms.macc.wisc.edu==== | 1210 W. Dayton 2838 Stevens UUCP: {harvard,rutgers,allegra,ucbvax} | | Madison, WI 53706 Madison 53705 !uwvax!vms3.macc.wisc.edu!anderson | ==608/263-6988=======608/238-4833===BITNET: anderson@wiscmacc===============
cosell@bbn.com (Bernie Cosell) (10/13/88)
In article <2610015@hpsal2.HP.COM> morrell@hpsal2.HP.COM (Michael Morrell) writes: }Does anyone know the exact definition of "point" (as in a 12-point font)? POINT SYSTEM: The system by which all typographic manterial is manufactured to sizes which are exact multiples of a point. The English and American point is 0.0138 in. or more accurately 72 points = 0.9966 inch. The Didot point used on the Continent is slightly larger, it is 0.376 mm, English point 0.351 mm. -from {\it Basic Typography} by John R. Biggs Note that this is a *design*size* when you're using it to refer to a font. There may well be *nothing* in the font itself that you can measure that is actually "12 points" long or high or anything else. __ / ) Bernie Cosell /--< _ __ __ o _ BBN Sys & Tech, Cambridge, MA 02238 /___/_(<_/ (_/) )_(_(<_ cosell@bbn.com
kjk@pbhyf.PacBell.COM (Ken Keirnan) (10/13/88)
In article <2610015@hpsal2.HP.COM> morrell@hpsal2.HP.COM (Michael Morrell) writes: >Does anyone know the exact definition of "point" (as in a 12-point font)? >Some references (most nroff manuals) say there are 72 points to the inch, >but others simply say (including my Webster's!!!) that a point is "nearly" >equal to 1/72 of an inch. Who is right? The "other" references. There are actually (Heaven help me if I am wrong :-)) 72.27 printers points to the inch. *Please* don't ask me why. I don't know. Ken Keirnan -- Ken Keirnan - Pacific Bell - {att,bellcore,sun,ames,pyramid}!pacbell!pbhyf!kjk San Ramon, California kjk@pbhyf.PacBell.COM
wnp@dcs.UUCP (Wolf N. Paul) (10/13/88)
In article <30767@bbn.COM> cosell@BBN.COM (Bernie Cosell) writes: * In article <2610015@hpsal2.HP.COM> morrell@hpsal2.HP.COM (Michael Morrell) writes: * }Does anyone know the exact definition of "point" (as in a 12-point font)? * * POINT SYSTEM: The system by which all typographic manterial is manufactured * to sizes which are exact multiples of a point. The English and American * point is 0.0138 in. or more accurately 72 points = 0.9966 inch. The Didot * point used on the Continent is slightly larger, it is 0.376 mm, English * point 0.351 mm. * -from {\it Basic Typography} by John R. Biggs * * Note that this is a *design*size* when you're using it to refer to a font. * There may well be *nothing* in the font itself that you can measure that is * actually "12 points" long or high or anything else. 1. The English point referred to above is often called the PICA POINT in contrast to the continental Didot point, which is sometimes referred to (at least in German typography, and when contrasting with Pica) the CICERO point. This refers to the traditional names for the respective 12-point size, which in the Anglo-American system is called PICA, and in the Didot System, in German at least, CICERO. 2. While the above comment about there not necessarily being anything measurable in a font, generally pointsize is considered to refer to the sum of x-height (i.e. the height of the lower case x and by inference of most l.c. chars.), descenders, and ascenders or (cap height - x height), whichever is larger. I am making this comment, because I have come across several DTP books and programs which measure point size just on the cap height, and that leads to specs and type sizes which differ from the standard, leading to much confusion. 3. Finally note that the relationship of x-height and cap height determines the visual size of a font -- i.e. HP Softfonts TmsRmn 12pt looks much bigger than Knuth's TeX Computer Modern Roman 12pt., because of the HP fonts' larger lower case characters. -- Wolf N. Paul * 3387 Sam Rayburn Run * Carrollton TX 75007 * (214) 306-9101 UUCP: killer!dcs!wnp ESL: 62832882 DOMAIN: dcs!wnp@killer.dallas.tx.us TLX: 910-380-0585 EES PLANO UD
rbr4@uhura.cc.rochester.edu (Roland Roberts) (10/13/88)
In article <2610015@hpsal2.HP.COM> morrell@hpsal2.HP.COM (Michael Morrell) writes: >Does anyone know the exact definition of "point" (as in a 12-point font)? To further add to the plethora of responses, the following are from the TeXbook, p57. 1 pica = 12 point 1 inch = 72.27 point 1 didot point = 1238 point 1 cicero = 12 didot point Roland Roberts BITNET: roberts@uornsrl Nuclear Structure Research Lab INTERNET: rbr4@uhura.cc.rochester.edu -- Roland Roberts BITNET: roberts@uornsrl Nuclear Structure Research Lab INTERNET: rbr4@uhura.cc.rochester.edu
wu@spot.Colorado.EDU (WU SHI-KUEI) (10/14/88)
In article <2610015@hpsal2.HP.COM> morrell@hpsal2.HP.COM (Michael Morrell) writes: >Does anyone know the exact definition of "point" (as in a 12-point font)? >Some references (most nroff manuals) say there are 72 points to the inch, >but others simply say (including my Webster's!!!) that a point is "nearly" >equal to 1/72 of an inch. Who is right? > > Michael Both. In "The ABC's of TYPOGRAPHY", the author writes: "...There are approximately 72 points to an inch. One point equals .0138 inch, which is close enough to 1/72 inch for the kinds of calculations we will be doing." Note: 1/.0138 = 72.4638 and 72/72.4638 = .9936, or not to worry! Just a guest here. In real life Carl Brandauer ncar!nbires!bdaemon!carl
henry@utzoo.uucp (Henry Spencer) (10/14/88)
In article <2610015@hpsal2.HP.COM>, morrell@hpsal2.HP.COM (Michael Morrell) writes...
]Does anyone know the exact definition of "point" (as in a 12-point font)?
]Some references (most nroff manuals) say there are 72 points to the inch,
]but others simply say (including my Webster's!!!) that a point is "nearly"
]equal to 1/72 of an inch. Who is right?
A point is historically one of these bizarre odd-sized units that just do
not come out to anything nice and clean and even. It is *almost* equal
to 1/72 of an inch. Not quite. Certain sloppy pieces of software (troff),
encouraged by certain sloppy pieces of hardware (the C/A/T), try to simplify
their lives by assuming that a point is exactly 1/72 of an inch. That does
not make it so. The difference is not large enough to matter a lot in many
cases, at least not to an untrained eye.
--
The meek can have the Earth; | Henry Spencer at U of Toronto Zoology
the rest of us have other plans.|uunet!attcan!utzoo!henry henry@zoo.toronto.eduwrs@pupthy.PRINCETON.EDU (William R. Somsky) (10/14/88)
In reply to Michael Morrell <2610015@hpsal2.HP.COM> morrell@hpsal2.HP.COM >> Does anyone know the exact definition of "point" (as in a 12-point font)? Roland Roberts <142@ur-cc.UUCP> rbr4@uhura.cc.rochester.edu writes: > ... the following are from the TeXbook, p57. > ... > 1 inch = 72.27 point > ... If you continue reading, you find on page 58 of the TeXbook: [Dangerous] The units have been defined here so that precise [ Bend ] conversion to sp is efficient on a wide variety of machines. In order to achieve this, TeX's "pt" has been made slightly larger than the official printer's point, which was defined to equal exactly .013837in by the American Typefounders Association in 1886 [cf. National Bureau of Standards Circular 570 (1956)]. ... Hence, if the American Typefounders Association definition is still the official one, we have: DEFINED (1886): 1 point = .013837 in DEFINED (19??): 1 in = 2.54 cm DEFINED (1983): 1 m = (speed of light in vacuum) x 1/299792458 s DEFINED (1977): 1 s = "9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom" So, if all my information is up to date, just grab youself a cesium-133 atom, get it to kick out a photon from its hyperfine transition in the ground state, count off (.013837)(.0254)(9192631770)/(299792458) wavelengths in a vacuum, and you'll have one point EXACTLY! However, if you're not an overly pedantic physicist, just take (1/72)in or (1/72.27)in or anything else about the same, and it'll probably be close enough for all practical purposes. :-) ------------------------------------------------------------------------ William R. Somsky Physics Dept ; Princeton Univ wrs@pupthy.Princeton.EDU PO Box 708 ; Princeton NJ 08544
wnp@dcs.UUCP (Wolf N. Paul) (10/14/88)
In article <142@ur-cc.UUCP> rbr4@uhura.cc.rochester.edu (Roland Roberts) writes: >To further add to the plethora of responses, the following are from the >TeXbook, p57. > > 1 pica = 12 point > 1 inch = 72.27 point > 1 didot point = 1238 point <------+ > 1 cicero = 12 didot point | > | | Surely you forgot a decimal point here and a didot point is 1.238 pica points! That would be a very unwieldy unit of measurement, even for those continental Europeans! :-) -- Wolf N. Paul * 3387 Sam Rayburn Run * Carrollton TX 75007 * (214) 306-9101 UUCP: killer!dcs!wnp ESL: 62832882 DOMAIN: dcs!wnp@killer.dallas.tx.us TLX: 910-380-0585 EES PLANO UD
tom@nsebln (10/14/88)
In notesgroup <comp.text> hpsal2!morrell (Michael) writes > Does anyone know the exact definition of "point" (as in a 12-point font)? > Some references (most nroff manuals) say there are 72 points to the inch, > but others simply say (including my Webster's!!!) that a point is "nearly" > equal to 1/72 of an inch. Who is right? The size of one point was standardized in 1886 for the American point system, and fixed at 0.01384 inches, or almost exactly 1/72 inch. Sandra L.Emerson, Karen Paulsell troff typesetting for UNIX systems Prentice-Hall, Inc., Englewood Cliffs, New Jersey 07632 1/72 is equal to 0.0138888..., so your Webster's is right. ------------------------------------------------------------------------ __ _ _____ _______ Thomas Krickstadt | \ | | / ____\ | ______| Nixdorf Software Engineering GmbH | |\ \ | | | |____ | |__ Voltastr. 1 | | \ \| | \___ \ | __| D 1000 Berlin 65 | | \ | ____| | | |_____ Phone: ++49 030 46007 130 |_| \__| \_____/ |_______| UUCP : unido!nixpbe!krickstadt.bln ------------------------------------------------------------------------
jaap+@andrew.cmu.edu (Jaap Akkerhuis) (10/14/88)
Bear in mind that all these nifty numbers hardly make any sense at all in the
real world. I know of at least two models of a typesetter from the same
manufacturer which have an apparently a different size for a point. This is not
a big deal, since it is marginal. However, it starts to become annoying when
you want to combine output of both versions in one document. The linelength
will vary enough to be noticable.
jaapchip@ateng.ateng.com (Chip Salzenberg) (10/14/88)
According to wu@spot.Colorado.EDU (WU SHI-KUEI): >In article <2610015@hpsal2.HP.COM> morrell@hpsal2.HP.COM (Michael Morrell) writes: >>Does anyone know the exact definition of "point" (as in a 12-point font)? > >In "The ABC's of TYPOGRAPHY", the author writes: > "...There are approximately 72 points to an inch. One point > equals .0138 inch, which is close enough to 1/72 inch for the > kinds of calculations we will be doing." Fine, for ballpark calculations. However, I know of at least one typesetter that actually produced *severely* misaligned text because the programmer ass_u_med that 1/72 inch was "close enough." Be exact. You'll regret it later if you aren't. -- Chip Salzenberg <chip@ateng.com> or <uunet!ateng!chip> A T Engineering Me? Speak for my company? Surely you jest! Beware of programmers carrying screwdrivers.
dns@sq.uucp (David Slocombe) (10/17/88)
In article <YXJVEOy00UkP40aWB1@andrew.cmu.edu> jaap+@andrew.cmu.edu (Jaap Akkerhuis) writes: >Bear in mind that all these nifty numbers hardly make any sense at all in the >real world. I know of at least two models of a typesetter from the same >manufacturer which have an apparently a different size for a point. This is not >a big deal, since it is marginal. However, it starts to become annoying when >you want to combine output of both versions in one document. The linelength >will vary enough to be noticable. Too right, Jaap! A publishing house a block away from us has a Linotron 101 laser phototypesetter which does not give you anything like an exact pica in the direction of the film motion, because, long ago, a serviceman repairing the machine went off without checking that the *analog* adjustment that controls the scale in that direction was reset correctly after he had repaired the machine. It was a Friday, and an awful lot of work had to be done over the weekend on all sorts of work-in-progress, so the staff "made do" and worked out how to adjust what they were specifying so that the actual physical measurements came out right. After that it was awfully hard to find a time when it would be OK for the serviceman to come back and readjust the machine, since you couldn't afford to have corrections on jobs started that weekend not come out with EXACTLY the same measures.... and the problem was renewing itself with each new job started! The upshot is that that Linotron 101 has been running with its scale set wrong ever since. Fortunately, in sqtroff there is a ".scale" request: .scale c numerator denominator [round | trunc] where: "c" is a single letter that is the new troff scale unit (or an old one if it is being redefined). "numerator" is a non-negative integer (or number register) with some already-existing scale-indicator attached. "denominator" is a positive integer or register. "round" and "trunc" are keywords that set the way fractions will be handled with this new scale-indicator. This new request was created to enable Europeans and fussy Americans to redefine the point and Pica (the default is still 1/72 inch), but you can imagine all the interesting uses it can be put to, including dealing with permanently-misadjusted phototypesetters! ---------------------------------------------------------------- David Slocombe (416) 963-8337 SoftQuad Inc. (800) 387-2777 (from U.S. only) 720 Spadina Ave. uucp: {uunet!attcan!utzoo, utai}!sq!dns Toronto, Ontario, Canada M5S 2T9 Internet: dns@sq.com
av@utacs.UTA.FI (Arto Viitanen) (10/17/88)
In article <2610015@hpsal2.HP.COM> morrell@hpsal2.HP.COM (Michael Morrell) writes: >Does anyone know the exact definition of "point" (as in a 12-point font)? >Some references (most nroff manuals) say there are 72 points to the inch, >but others simply say (including my Webster's!!!) that a point is "nearly" >equal to 1/72 of an inch. Who is right? > > Michael In his The TeXbook, Donald E, Knuth says "... was defined exaclty .013837 in by the American Typefounders Association in 1886. ... The new definition 72.27 pt = 1in is not only better for calculation, it is also easier to remember". So one inch is 72.27 points. Arto Viitanen University Of Tampere, Department of Computer Science P.O.Box 607 SF-33101 TAMPERE FINLAND av@utacs.uta.fi, av@comic.uta.fi
bts@sas.UUCP (Brian T. Schellenberger) (10/18/88)
In article <217@dcs.UUCP> wnp@dcs.UUCP (Wolf N. Paul) writes: |In article <30767@bbn.COM> cosell@BBN.COM (Bernie Cosell) writes: | in a font, generally pointsize is considered to refer to the sum of x-height | (i.e. the height of the lower case x and by inference of most l.c. chars.), | descenders, and ascenders or (cap height - x height), whichever is larger. | | I am making this comment, because I have come across several DTP books and | programs which measure point size just on the cap height, and that leads to | specs and type sizes which differ from the standard, leading to much | confusion. Does the height of a parenthesis work well as an approximation? I ask because this is one that is suggested by Knuth. -- --Brian, __________________________________________________ the man from |Brian T. Schellenberger ...!mcnc!rti!sas!bts Babble-On |104 Willoughby Lane work: (919) 467-8000 x7783 ____________________________|Cary, NC 27513 home: (919) 469-9389
wnp@dcs.UUCP (Wolf N. Paul) (10/19/88)
In article <642@sas.UUCP> bts@sas.UUCP (Brian T. Schellenberger) writes: >In article <217@dcs.UUCP> wnp@dcs.UUCP (Wolf N. Paul) writes: >| in a font, generally pointsize is considered to refer to the sum of x-height >| (i.e. the height of the lower case x and by inference of most l.c. chars.), >| descenders, and ascenders or (cap height - x height), whichever is larger. >Does the height of a parenthesis work well as an approximation? I ask >because this is one that is suggested by Knuth. If Knuth says it, it's well worth listening to. I guess it depends on the font design. In most cases parentheses would be as tall as the ascenders; whether it reaches below the baseline sufficiently to be used as an indicator of pointsize depends on the design of the font. I should also pass on what some have pointed out to me: in the traditional world of movable (lead) type, point size refers to the height of the slug on which the letters of a given font are mounted, not necessarily to any measurable feature of the printed image. Thus, you could have tiny characters mounted on a 28pt. slug and it would be considered -- technically -- a 28pt. font. But I suggest that for practical purposes, and in a computerized environment where characters in a font are not mounted on slugs :-) my definition works well enough. Wolf -- Wolf N. Paul * 3387 Sam Rayburn Run * Carrollton TX 75007 * (214) 306-9101 UUCP: killer!dcs!wnp ESL: 62832882 DOMAIN: dcs!wnp@killer.dallas.tx.us TLX: 910-380-0585 EES PLANO UD