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Abstract
The isomath package provides tools for a mathematical style that conforms to the International Standard ISO 800002 and is common in science and technology. It changes the default shape of capital Greek letters to italic, sets up bold italic and sansserif bold italic math alphabets with Latin and Greek characters, and defines macros for markup of vector, matrix and tensor symbols.
Contents
In their style guides, e. g. [typefaces], [checklist], [SI], [fonts_for_symbols], [RedBook], [GreenBook], many international scientific organisations recommend layout rules for mathematics in line with the International Standard [ISO800002].
International standard layout rules
The overall rule is that symbols representing physical quantities (or variables) are italic, but symbols representing units, or labels, are roman.
Symbols for vectors and matrices are bold italic, symbols for tensors are sansserif bold italic.
The above rules apply equally to letter symbols from the Greek and the Latin alphabet.
TeX's default mathematical style deviates from this rules in several points:
Capital Greek letters default to upright shape,
small Greek letters are excluded from font changes with the math alphabet commands, and
the \vec command produces an arrow accent.
The isomath package implements an “ISO” math style, provides new math alphabets with bold italic and sansserif bold italic type and macros for semantic markup of vector, matrix and tensor symbols. It can be combined with most packages for mathematical typesetting (see isomathtest.tex and the sections on alternatives and conflicts).
Isomath builds on the package fixmath by Walter Schmidt to change the default mathematics layout to the “ISO” math style:
Capital Greek letters are typeset in italic shape by default.
Both, Greek and Latin letters change shape if a different math alphabet is used.
Caution!
Be careful with Greek letters in the argument of \mathit, \mathrm, \mathbf, \mathsf, and \mathtt. By default, these math alphabets use text fonts. Fonts in OT1 text font encoding have capital (but not small) Greek letters at the expected places, T1 encoded text fonts have no Greek letters at all.
See the examples section on how to get upright small Greek letters in mathematical context.
Isomath defines the new math alphabets:
\mathbfit 
boldface italic 
vector and matrix symbols 
\mathsfit 
sansserif italic 
optional (see OMLmath*_ options) 
\mathsfbfit 
sansserif bold italic 
tensor symbols 
For compatibility with earlier versions and related packages, the new math alphabets are also available under the aliases \mathbold, \mathsans, and \mathboldsans.
The rmdefault and sfdefault options set the font family used for these alphabets.
Caution!
Using the new math alphabets for numbers can result in upright oldstyle numbers instead of italic ones, because some italic math fonts (e. g., cmr, cmbr) contain oldstyle in place of italic digits.
The following commands set the argument in an ISOconforming math alphabet:
\vectorsym, \matrixsym 
bold italic for Greek and Latin letters, bold upright for numbers 
\tensorsym 
sansserif bold italic 
Make sure that LaTeX can find isomath.sty and load it with:
\usepackage{isomath}
Optionally redefine the standard vector macro \vec:
\renewcommand{\vec}{\vectorsym}
(see also Options, Examples, and isomathtest.tex).
Family for serif math fonts (\mathrm, \mathbf, \mathit, \mathbfit). The default is to use the corresponding text font family (the value of \rmdefault). The font must be available in OML font encoding (cf. Table 3).
Family for sansserif math fonts. The default is cmbr because most sansserif fonts define the Computer Roman font cmm as OML substitution (see Table 4).
There are only few sans serif fonts in OML font encoding:
Name 
Package 
Comment 

cmbr 
Computer Modern Bright, bitmap, slightly lighter than cmss (Type 1 fonts with hfbright) 

fav 
Arev (Vera Sans), large xheight 

hvm 
Helvetica Math, commercial, free bitmap version 

iwona 
Iwona, humanistic sans serif, some shapes very similar to roman 

jkpss 
Kepler Sans, quite light 

llcmss 
LX Fonts, “slide fonts”, very wide, large xheight 
To improve the chances of finding a matching sans serif math font, the fonts fav, iwona, jkpss, and llcmss can be scaled with the scaled option (cf. Examples). For other fonts, the option is ignored.
The definition of new math alphabets can lead to a “too many math alphabets used in version normal” error. As a workaround, this option tells isomath to reuse the existing \mathbf and \mathsf alphabets for italic bold and sansserif bold.^{1}
To access the upright shapes, the corresponding \textbf and \textsf commands might be used. Watch for sideeffects, as these commands switch to text mode so that the font settings in the embedding text apply.
The OMLmath* options bind the corresponding \math* command to an OMLencoded font.
The \mathsfit alphabet is not required for ISO conforming mathematical layout and therefore only defined if the OMLmathsfit argument is used.
The predefined math alphabets \mathrm, \mathbf, and \mathtt use OT1 encoded text fonts with ligatures and accents in place of the small Greek letters. The OMLmath* options enable the use of small Greek letters in math alphabet commands, e. g. \mathrm{\pi}, if the corresponding font is available in OML font encoding. Table 3 lists font families supporting the OML encoding.
Caution!
If no matching OML encoded font is found, LaTeX's substitute mechanism selects a font with different font attributes (for all letters, not only Greek). Currently, only the mathdesign package provides upright fonts in OML encoding. Many font packages define an italic font as OML substitute for roman fonts.
With some packages, these options can result in a “too many math alphabets used in version normal” error.
Use scaled arev fonts for the sans serif math alphabets (adapt the scaling factor to your needs):
\usepackage[sfdefault=fav,scaled=0.875]{isomath}
Define the \mathsfit sansserif italic math alphabet:
\usepackage[OMLmathsfit]{isomath}
The \mathbfit and \mathsfbfit alphabets do not have a different weight in the bold math version because the number of LaTeX math fonts providing extrabold or ultrabold series is negligible.
As a workaround, use the heavier arev font, scaled to 0,875, in the bold version of \mathsfbfit:
\usepackage{isomath} \DeclareFontShape{OML}{fav}{bx}{it}{<> s * [0.875] zavmbi7m}{} \SetMathAlphabet{\mathsfbfit}{bold}{OML}{fav}{bx}{it}
See also the isomathtest.tex test document.
Of the following methods, only the first requires isomath:
Use isomath and the mathdesign package:
\usepackage[utopia]{mathdesign} \usepackage[OMLmathrm,OMLmathbf]{isomath}
Now, e. g., \mathrm{\pi} and \mathbf{\pi} work as expected.
To get upright small Greek letters without affecting other fonts, set the math alphabet manually to one of the three mathdesign fonts, e. g.:
\SetMathAlphabet{\mathbf}{normal}{OML}{mdput}{b}{n}
(check if the letter shapes match with the rest of the document).
Use a package that provides macros for upright Greek letters in math mode:
\otheralpha ... \otherOmega 

\alphaup ... \Omegaup 

\alphaup ... \Omegaup 

\upalpha ... \upOmega 
Use an upright text character (requires a matching LGRencoded Greek text font). The following lines redefine \pi to set the mathematical constant pi upright:
\usepackage[LGR,T1]{fontenc} \usepackage[greek,british]{babel} \usepackage{amsmath} \let\mathpi\pi \renewcommand{\pi}{\text{\textrm{\greektext p }}}
Use the text character with the alphabeta package from the lgrx bundle:
\usepackage{amsmath} \usepackage{alphabeta}
and in the body
$ u = 2 \text{\pi} r $
This section discusses LaTeX math font selection, the OML font encoding, and the relation of LaTeX and Unicode mathematical typesetting.
There are three complementary methods to set font attributes in LaTeX math mode: LaTeX 2e font selection [fntguide] describes math alphabets and math versions, several extension packages provide alternative math styles.
TeX's math alphabets correspond to the mathematical alphanumeric symbols block in Unicode. Both are “to be used for mathematical variables where style variations are important semantically”. The font guide [fntguide] defines in section 3:
Some math fonts are selected explicitly by oneargument commands such as \mathsf{max} or \mathbf{vec}; such fonts are called math alphabets.
Math fonts [...] have the same five attributes as text fonts: encoding, family, series, shape and size. However, there are no commands that allow the attributes to be individually changed. Instead, the conversion from math fonts to these five attributes is controlled by the math version.
The predefined math alphabets are:
\mathnormal
default^{2}
\mathrm
roman^{3}
\mathbf
bold roman
\mathsf
sans serif
\mathit
text italic
\mathtt
typewriter
\mathcal
calligraphic
\mathnormal is used by default for alphanumeric characters in math mode. It sets the letter shape according to character class and math style. (Table 1 shows the default letter shapes for common math styles).
The specifier “roman” is ambiguous: roman shape stands for upright, while roman type stands for serif (as opposed to sans serif).
Many packages define additional math alphabets (cf. Table 6).
In contrast to the similar named text commands, math alphabets are not orthogonal, e. g., the code $\mathit{\mathbf{a}}$ sets the letter a in upright bold type.
Math versions specify the mapping from commands for mathematical symbols and math alphabets to a set of mathematical fonts^{4}. They are intended for mathematical content in a special context like a bold section heading. Selecting a math version resembles the individual selection of text font attributes.
Some alternatives to set the letter a in a bold upright sansserif font:
Text 
Math 

\textbf{\textsf{a}} 
$\bm{\mathsf{a}}$ 
\bfseries \textsf{a} 
\mathversion{bold} $\mathsf{a}$ 
\bfseries \sffamily a 
$\mathsfbf{a}$ 
The predefined math versions are normal and bold with the following defaults for nonspecified font attributes:
attribute
normal
bold
type
serif
serif
weight
medium
bold
shape
upright
upright
Packages can define additional math versions, e. g., the kpfonts package defines a sans math version (another sans math version example is available from a comp.text.tex post`) and the wrisym package defines a mono math version.
Math versions can only be changed outside of math mode. The commands \boldsymbol (amsmath) and \bm (bm) behave like “inline math versions”: they typeset their argument using the fonts of the bold math version but can be used inside math mode.
The number of mathematical symbols exceeds the maximal number of characters in a TeX font file by an order of magnitude: Unicode defines about 2500 mathematical characters [tr25], font files used by 8bit TeX engines are limited to 256 characters. The standard math fonts adhere to the original limit of 128 characters. Grouping math fonts with common characteristics in math versions simplifies the setting of font attributes for mathematical expressions. TeX limits the number of (symbol + alphanumeric) fonts per math version to 16.
A math style is a documentlevel feature that determines the default letter shape in math mode (i. e. the shape attribute of letters in the \mathnormal math alphabet).^{5} LaTeX defaults to the “TeX” math style (without naming it such). Alternative math styles are introduced by extension packages (Table 2).
The mathstyle option of unicodemath changes also the shape attribute of other math alphabets (see also section the unicodemath package).
math style 
latin 
Latin 
greek 
Greek 

TeX 
it 
it 
it 
up 
ISO 
it 
it 
it 
it 
French 
it 
up 
up 
up 
upright 
up 
up 
up 
up 
math style 
Package 
Option(s) 

ISO 

isomath 

slantedGreeks 

mathstyle=iso 

greekuppercase=italicized 

slantedGreek 

slantedGreek 

mathstyle=ISO 

French 
upright 

frenchstyle (or upright) 

mathstyle=french 

uppercase=upright, greeklowercase=upright 

mathstyle=french 

upright 

mathstyle=upright 

mathstyle=upright 
The equal treatment of Latin and Greek letters in the “ISO” math style is best achieved with a font that contains all required letters in one file.
There is only one established LaTeX font encoding that contains Latin and Greek letters, the OML font encoding. The standard Greek font encoding T7 is just a “reserved name” and the defacto standard Greek text font encoding LGR has no Latin letters. Unfortunately, OML support is limited to a few (mostly italic) fonts.
The LaTeX font encodings guide [encguide] names the OML encoding TeX math italic and defines:
The OML encoding contains italic Latin and Greek letters for use in mathematical formulae (typically used for variables) together with some symbols.
The reference to italic shape is odd:
No other font encoding is specific to a font shape.
The different font selection and the semantic of font features in mathematical formulae do not interfere with the font encoding: Both, \DeclareSymbolFont and \DeclareMathAlphabet require a shape argument. Thus it is possible to set up OML encoded math alphabets in roman {n} as well as italic {it} shape without conflicts.
This seems to be more a remnant of preNFSS times than a necessary restriction – there is only one OML encoded font in Knuth's Computer Modern fonts: Computer Modern Math Italic (cmmi).
Proposals:
Drop the italic from the definition. Optionally add an explanation:
The OML encoding contains Latin and Greek letters for use in mathematical formulae (typically used for variables) together with some symbols. It first appeared in the Computer Modern Math Italic (cmmi) font.
The name TeX math italic can be interpreted as “the encoding of Computer Modern Math Italic” rather than “an encoding for math italic” fonts.
A less confusing name would be TeX math letters or Original/Old Math Letters. The latter would also explain the acronym OML.
Unfortunately, support for the OML encoding is missing for many font families even if the text font defines Greek letters. Supported font families can be found searching for oml*.fd files and grepping for DeclareFont.*OML in *.sty files.
Table 3 lists the findings for a selection of TeXLive 2012 + some additionally installed font packages.
If there is an alias (substitution) from the text font to a mathvariant, only the text font is listed.
Many text fonts define substitutions also for upright shape, however mapping to an italic variant of the OML encoded font. These are not listed as supporting m/n or bx/n here.
Table 4 lists some fonts that define cmm as OML substitution. With isomath, a better matching substitution can be set using the rmdefault or sfdefault options.
Name 
Family (package) 
m/it 
bx/it 
m/n 
bx/n 

antt 
Antykwa Torunska (anttor) 
✓ 
✓ 

cmr 
Computer Modern 
✓ 
✓ 

ccr 
Concrete Roman (concmath) 
✓ 
✓ 

cmbr 
CM Bright (cmbright) 
✓ 
✓ 

hlh 
Lucida 
✓ 
✓ 

hfor 
CM with oldstyle digits 
✓ 
✓ 

iwona 
Iwona (sans serif) (iwona) 
✓ 
✓ 

iwonal 
Iwona light 
✓ 
✓ 

iwonac 
Iwona condensed 
✓ 
✓ 

iwonalc 
Iwona light condensed 
✓ 
✓ 

jkp 
Kepler Serif (kpfonts) 
✓ 
✓ 

jkpw 
Kepler Serif wide 
✓ 
✓ 

jkpvos 
Kepler Serif oldstyle 
✓ 
✓ 

jkpvosw 
Kepler Serif oldstyle wide 
✓ 
✓ 

jkpl 
Kepler Serif light 
✓ 
✓ 

jkplw 
Kepler Serif light wide 
✓ 
✓ 

jkplvos 
Kepler Serif light oldstyle 
✓ 
✓ 

jkplvosw 
Kepler Serif light os wide 
✓ 
✓ 

jkpss 
Kepler Sans (kpfonts) 
✓ 
✓ 

jkpssvos 
Kepler Sans oldstyle 
✓ 
✓ 

jtm 
expanded Times (jamtimes) 
✓ 
✓ 

llcmm 
LX Fonts (sans serif) (lxfonts) 
✓ 
✓ 

lmr 
Latin Modern Roman (lmodern) 
✓ 
✓ 

mak 
Kerkis (kerkis) 
✓ 

kurier 
Kurier (sans serif) (kurier) 
✓ 
✓ 

kurierc 
Kurier condensed 
✓ 
✓ 

kurierl 
Kurier light 
✓ 
✓ 

kurierlc 
Kurier light condensed 
✓ 
✓ 

mdbch 
Math Design Charter (mathdesign) 
✓ 
✓ 
✓ 
✓ 
mdput 
Math Design Utopia 
✓ 
✓ 
✓ 
✓ 
mdugm 
Math Design Garamond 
✓ 
✓ 
✓ 
✓ 
neohellenic 
Neohellenic (gfsneohellenic) 
✓ 

ntxmi 
Times (newtx) 
✓ 
✓ 

nxlmi 
Libertine (newtx) 
✓ 
✓ 

plcm 
CM (PLaTeX) 
✓ 

ptmom 
Times (Omega or MBTimes) 
✓ 
✓ 

ptmomu 
Times (Omega or MBTimes) 
✓ 
✓ 

ptmcm 
Times (mathptmx) 
✓ 

pxr 
Palatino (pxfonts) 
✓ 
✓ 

qpl 
Palatino/Pagella (qpxmath) 
✓ 
✓ 

qtm 
Times/Termes (qtxmath) 
✓ 
✓ 

txr 
Times (txfonts) 
✓ 
✓ 

udidot 
Didot (gfsdidot) 
✓ 

ywclm 
(greektex) 
✓ 
✓ 

zavm 
Arev (Vera SansSerif) 
✓ 
✓ 

zplm 
Palatino (mathpazo) 
✓ 
✓ 

zpple 
Palatino 
✓ 
✓ 

ztmcm 
Times (mathptmx) 
✓ 

zer 
Computer Modern (zefonts) 
✓ 
✓ 
Family 
Name 

bch 
Charter (psnfss) 
pag 
Avant Garde (psnfss) 
pbk 
Bookman (psnfss) 
pcr 
Courier (psnfss) 
phv 
Helvetica (psnfss) 
pnc 
New Century Schoolbook (psnfss) 
ppl 
Palatino (psnfss) 
ptm 
Times Roman (psnfss) 
put 
Utopia (psnfss) 
pzc 
Zapf Chancery (psnfss) 
uag 
Avant Garde (avantgar) 
ubk 
Bookman (bookman) 
ucr 
Courier (courier) 
ucrs 
Courier 
unc 
New Century Schoolbook (psnfss) 
uni 
Universal (universa) 
uhv 
Helvetica (helvetic) 
upl 
Palatino (palatino) 
utm 
Times (times) 
uzc 
Zapf Chancery (zapfchan) 
This section compares math font selection in LaTeX and Unicode. It suggests a set of 14 math alphabet commands that covers all Unicode mathematical alphanumeric symbols and discusses compatibility issues between math typesetting with traditional (8bit) TeX engines versus the unicodemath package for Unicodeenabled TeX engines (XeTeX, LuaTeX).
The technical report [tr25] presents an indepth discussion of the mathematical character repertoire of the Unicode Standard as well as mathematical notation in general.
Chapter 2 Mathematical Character Repertoire of [tr25] lists 14 Mathematical Alphabets in Table 2.1. These mathematical alphabets are a superset of the predefined math alphabets in the LaTeX core.
Unicode assigns code points to most letters of the mathematical alphabets in the mathematical alphanumeric symbols Unicode block. The plain (upright) letters have been unified with the existing characters in the Basic Latin and Greek blocks.
Table 5 maps the 14 Unicode mathematical alphabets to LaTeX commands according to the naming scheme below. Table 6 lists the status of LaTeX support for the mathematical alphanumeric symbols.
The naming scheme is an extension of the predefined math alphabet commands with the established shortcuts:
bf 
bold 
it 
italic 
cal 
script (calligraphic) 
frak 
fraktur 
bb 
doublestruck (blackboard bold) 
sf 
sans serif 
combined to commands in the form \math<type><weight><shape>.
The <type>, <weight>, and <shape> specifiers are optional (defaults depend on the math version). Their order matches the names of Unicode Mathematical Alphanumeric Symbols.
Examples:
\mathbf{d} % MATHEMATICAL BOLD SMALL D \mathsfbfit{d} % MATHEMATICAL SANSSERIF BOLD ITALIC SMALL D.
serifs 
weight 
shape 
symbols 
math alphabet 

serif 
medium 
upright 
Latin/Greek/digits^{6} 
\mathrm 
bold 
Latin/Greek/digits 
\mathbf 

italic 
Latin/Greek 
\mathit 

bold 
italic 
Latin/Greek 
\mathbfit 

script 
Latin 
\mathcal 

bold 
script 
Latin 
\mathbfcal 

fraktur 
Latin 
\mathfrak 

doublestruck 
Latin/digits 
\mathbb 

bold 
fraktur 
Latin 
\mathbffrak 

sans serif 
Latin/digits 
\mathsf 

sans serif 
bold 
Latin/Greek/digits 
\mathsfbf 

sans serif 
italic 
Latin 
\mathsfit 

sans serif 
bold 
italic 
Latin/Greek 
\mathsfbfit 
monospace 
Latin/digits 
\mathtt 
Most commonly used math alphabets are supported either by the TeX kernel or additional packages. Full support is only provided by the unicodemath package.
style 
math alphabet 
package, comment 

plain^{6} 
\mathrm 
predefined^{7} 
\mathup 

bf 
\mathbf 
predefined^{7} 
it 
\mathit 
predefined^{7} 
bf it 
\mathbfit 
isomath^{8} 
\mathbold 

\boldsymbol 

\bm 

cal 
\mathcal 
predefined^{9} 
\mathscr 

bf cal 
\mathbfscr 

frak 
\mathfrak 

bf frak 
\mathbffrak 

bb 
\mathbb 

\mathbbm 

\mathds 
dsfont (doublestoke) 

sf 
\mathsf 
predefined^{7} 
sf bf 
\mathbfsfup 

sf it 
\mathsfit 
isomath^{8} 
sf bf it 
\mathsfbfit 
isomath^{8} 
\mathbold 

\mathbfsfit 

tt 
\mathtt 
predefined^{7} 
Users of UTF8 enabled TeX engines (XeTeX, LuaTeX) can typeset mathematics with the experimental unicodemath package by Will Robertson. It provides a LaTeX interface to OpenType fonts with math support, e. g., Asana Math, Cambria Math, New Euler or XITS, with commands to access the complete mathematical character repertoire of the Unicode Standard.
LaTeX math font selection methods with unicodemath:
Math alphabets map to a range of the mathematical alphanumeric symbols block in the current font (or a substitution defined with the range math font option).
Some command names differ from the predefined math alphabets or the above naming scheme:
LaTeX 
unicodemath 

\mathbf 
\mathbfup 
\mathsf 
\mathsfup 
\mathsfbf 
\mathbfsfup 
\mathsfbfit 
\mathbfsfit 
With unicodemath, \mathbf, \mathsf, and \mathsfbf behave similar to “inline math versions”: they consider the math style for upright vs. italic shape. Compatibility can be achieved via the options boldstyle=upright and sansstyle=upright.
\mathbfsfit reverses the order of the sf and bf selectors, so that, e. g., the Unicode character MATHEMATICAL SANSSERIF BOLD ITALIC CAPITAL A is selected by the nonmnemonic \mathbfsfit{A}.
Math versions can be set up using the syntax \setmathfont[version=<version name>,<font features>]{<font name>}
Several math styles are supported with the mathstyle package option that accepts the values TeX, ISO, french, upright, and literal.
It is hoped, that in the future more font families will support the OML encoding in normal and bold weight as well as upright and italic shape. This would be a major step towards a LaTeX equivalent of the mathematical alphanumeric symbols Unicode block.
This should be (relatively) easy to achieve via virtual fonts when the glyphs for the Greek letters already exist. Examples are Latin Modern, Kerkis, GFS Neohellenic, LX Fonts and KPSerif.
Upright small Greek letters in \mathrm would enable the specification of the constant pi, Myons, Pions, alphaparticles, photons, and neutrinos with math alphabets. (With mathdesign fonts, this is already possible today.)
With the development of the unicodemath package, an interesting alternative for ISOconforming math typesetting became available to users of Unicodeenabled TeX engines (XeTeX or LuaTeX).
Quantities and units – Part 2: Mathematical signs and symbols to be used in the natural sciences and technology: http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=31887.
Quantities and units, Superseded by [ISO80000].
National Institute of Standards and Technology (NIST), Typefaces for Symbols in Scientific Manuscripts: http://physics.nist.gov/cuu/pdf/typefaces.pdf.
National Institute of Standards and Technology (NIST), SI Unit rules and style conventions Check List for Reviewing Manuscripts: http://physics.nist.gov/cuu/Units/checklist.html.
International Union of Pure and Applied Chemistry (IUPAC), On the use of italic and roman fonts for symbols in scientific text, (Revised December 1999): http://old.iupac.org/standing/idcns/fonts_for_symbols.html.
Bureau international des poids et mesures (BIPM), The International System of Units (SI): http://www.bipm.org/en/si/si_brochure/.
International Union of Pure and Applied Chemistry (IUPAC), Quantities, Units and Symbols in Physical Chemistry, 3rd edition, RSC Publishing, Cambridge 2007: [ISBN 0 85404 433 7; ISBN13 978 0 85404 433 7].
International Union of Pure and Applied Physics (IUPAP), Symbols, Units, Nomenclature and Fundamental Constants in Physics: http://metrology.wordpress.com/measurementprocessindex/iupapredbook/indexiupapredbook/.
Claudio Beccari, Typesetting mathematics for science and technology according to ISO 31 XI, TUGboat, Volume 18, 1997, No. 1: http://www.tug.org/TUGboat/tb181/tb54becc.pdf.
Frank Mittelbach, Robin Fairbairns, Werner Lemberg, LaTeX3 Project Team, LaTeX font encodings: http://mirror.ctan.org/macros/latex/doc/encguide.pdf.
LaTeX3 Project Team, LaTeX 2e font selection: http://mirror.ctan.org/macros/latex/doc/fntguide.pdf.
Barbara Beeton, Asmus Freytag, Murray Sargent III, Unicode Support for Mathematics, Unicode Technical Report #25: http://www.unicode.org/reports/tr25/.
Barbara Beeton: Unicode and math, a combination whose time has come – Finally!, TUGBoat, 21#3, 2000: http://www.tug.org/TUGboat/Articles/tb213/tb68beet.pdf.