# 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.

#### 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: ‘Christian Lawson-Perfect’, ‘Navier–Stokes equation’.

#### 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.

Online, use <h2> and <h4> 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. Online, we no longer place attributions at the bottom of pages. 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. We do not italicise hyperlinks online.

Website links should simply be put in <a> tags, and not use italics.

#### maths

Online, maths should be typeset in MathJax (in between single dollar signs for inline, and in between double dollar signs for their own line). Don’t overuse it with numbers.

#### 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 punctuating 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…’.

#### 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.

#### 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 $\nabla^2 \phi = 0$).

• ### Read Issue 03 now!

Fractional calculus, counting divisors, whether voting can ever be fair and much more
• ### Things to make

Platonic shapes from tube maps, flexagons, and more mathematical craft
• ### Read Issue 02 now!

The joy of Jacobians | Fields Medallist Artur Avila | Fractograms | Nash's legacy | The perils of p-values

• ### Optimal Pac-Man

Ghostbusting with graph theory
• ### Reinventing 2D

What a difference a matrix makes