# Chalkdust style guide

Conforming to a style guide over all Chalkdust content—both paper and online—promotes clarity and projects professionalism. Online, people read our articles on many different devices, and following this guide ensures our articles look good everywhere.

In general, we follow the Guardian style guide for words and the Journal of Fluid Mechanics for maths. If it is not listed below, check these sources. This is a working document and can be updated.

Latest version: 10 March 2021.

### capital letters

In general, avoid. See the Guardian style guide and scroll down to ‘capitals’. Do Not Write Headings Or Titles Like This. Instead write them like this.

### d, the differential

Upright, not italic (use \mathrm{d}). Use for both derivatives and in integrals, so $$\frac{\mathrm{d}y}{\mathrm{d}x} \quad \text{and} \quad \int \mathrm{d}x.$$

### dashes

The use of em dashes—the long lines often used like brackets—is preferred to single dashes (which differs from the Guardian). Use single dashes for double-barrelled names if that person uses a dash (not always true, especially for Spanish names), but use double dashes for items named after two people. For example:

• Hugo Castillo Sánchez (no dash)
• Christian Lawson-Perfect (single dash)
• Navier--Stokes equation (double dash)

### dates

Use the format ‘25 December 2017’ (day month year, no commas and no ‘th’).

### e, the exponential number

Upright, not italic (use \mathrm{e}).

### eg

Means ‘for example’. No dots.

### fractions

Avoid using small fractions in text, eg $\frac{xy}{ab}$. In text and in sub- and superscripts use $xy/ab$, but use full-sized fractions for whole-line maths.

### headings

Online, use <h2> and <h3> tags only. Do not add extra formatting, such as bold or centre-align. Do not use images, either as titles or as bullet points (bad for mobile).

### horizontal lines

Avoid using horizontal lines (<hr> tags) unless you are adding something separate to the article at the bottom.

### i, the imaginary number

Upright, not italic (use \mathrm{i} or \ii in print).

### ie

Means ‘that is’. No dots.

### images

All images need attributions in their captions, including header images. Full instructions can be found on the page for sourcing images correctly on the Chalkdust website. Examples:

### italics

Use italics for the titles of books, films, newspapers and journal articles, as well as foreign words and phrases, poetry and scientific names. We italicise ‘Chalkdust’ in print paragraphs, but not in print headings or at all online.

### links

Website links should simply be put in <a> tags, and not be formatted in any other way.

### mathematics

Online, mathematics should be typeset in MathJax (in between single dollar signs for inline, and in between double dollar signs for their own line). MathJax allows you to use LaTeX syntax. Try not to overuse it with numbers: there is no need for maths formatting in phrases like ‘the 12 days of Christmas’!

The word ‘maths’ or ‘mathematics’ should be lowercase: see subjects.

### matrices

In print, should be in sans-serif bold italic, but online this is hard to achieve, so instead use sans-serif bold, eg $\boldsymbol{\mathsf{A}}\boldsymbol{v} = \lambda \boldsymbol{v}$ (use \boldsymbol{\mathsf{A}}).

### names of people

We do not use titles. Say ‘David Colquhoun’ on first mention, followed by either ‘David’ or ‘Colquhoun’, rather than ‘Professor David Colquhoun’ followed by ‘Prof. Colquhoun’. If we have to use titles (for example, when directly quoting another source), they are punctuated accordingly: Prof., Dr, Miss, Mr, Mrs, Ms. This policy reduces the barrier between academics and the general public. Do, however, say in author bylines that ‘David Colquhoun is professor of…’. There is no full stop after a middle initial (John F Kennedy).

### numbers

Spell out from one to nine; numerals from 10 to 999,999; thereafter use m, bn or tn for sums of money, quantities or inanimate objects in copy, eg 5m tonnes of coal, 30bn doses of vaccine, £50tn; but million or billion for people or animals, eg 1 million people, 25 million rabbits, the world population is 7 billion, etc.

### paragraph spacing

Online, if you feel you need to add extra vertical space to avoid clashing with an image, you can’t. Either move the image somewhere else, or set the alignment of the image to centre-align.

### parametrise, parametrisation

Not ‘parameterise’, although this is also acceptable English, on the basis that you are not actually turning the curve into a parameter.

### quotation marks

Typically we are not very good at policing this, but use double quotes for quoting actual speech, and single quotes for everything else.

### spelling differences

Use British English spellings and terminology, including -ise endings. For example: anticlockwise, favourite, maths, summarise, minimise.

### subjects

Names of academic subjects take lowercase: eg mathematics, maths, physics, oncology. This matches the policy for job titles which is also to take lowercase: eg ‘Trachette Jackson is professor of mathematics at the University of Michigan.’

### temperature

Use the degree sign but not for Kelvin, eg 25°C, 80°F, 300K. (This differs from the Guardian).

### units

In print, use \unit[m]{100}. Online, use ‘100m’ (no space). Use units appropriate for a British audience in print (generally metric but miles for long distances, stone for human-ish weights, the size of Wales for large areas) but consider an international audience for the online version.

### vectors

Should be in bold italic, $\boldsymbol{r} = (x,y,z)$ (use \boldsymbol{r}). This includes nabla but not the Laplacian (so $\boldsymbol{\nabla}\cdot\boldsymbol{u}=0$ but $\nabla^2 \phi = 0$).

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We review the sixth of this year's nominees for the Book of the Year
• ### Why Study Mathematics?

We review the fifth of this year's nominees for the Book of the Year
• ### Molly and the Mathematical Mystery

We review the fourth of this year's nominees for the Book of the Year