With a "c" when it's a noun; with an "s" when it's a verb. 

I always carry my driving licence with me for identification.

The government has agreed to license the sale of firearms.

use hyphen

Short for linear accelerator. Capital L when referring to one of CERN's Linacs, otherwise lower case. Add a numeral with no space when differentiating between CERN's linear accelerators. 

Linac2 started up in 1978 as a successor to Linac1. 

Links should always be in the form:

<a href="link_url_here">Link text here</a>.

Never show the reader the URL; keep it within a word or sentence. 

So: 

For CERN's style guide for web texts, click here.

NOT

For CERN's style guide for web texts, click here: https://test-static-04.web.cern.ch

LHC Injectors Upgrade project

Laboratori Nazionali di Frascati ​(Frascati National Laboratory)

Spell out in first use then use acronym for the CERN Courier

All official CERN websites should use the CERN logo, with the following conditions:

use hyphen, also for Short-Baseline

but use a hyphen in the past tense: long-listed

Lattice QCD

Spell out in first use then use acronym for the CERN Courier

The number of particles per unit area per time, multiplied by the opacity of the target (its impenetrability) to electromagnetic radiation.

Luminosity is measured in barns per second: b^-1s^-1

Luminosity is an important measure of the performance of a particle accelerator.

use hyphen

not Marseille in the CERN Courier

"Has mass" – the opposite of "massless". Does not mean "is large".

Though the up quark is a massive particle, it is not very big.

The subtle distinctions between these (and between other so-called modal verbs) are gradually disappearing, but they still matter to many readers and can be useful.

Medical Isotopes Collected from ISOLDE (medical applications facility at ISOLDE)

Do not add the word "with" after meet or met. Write:

I met John the other day and tomorrow I will meet his wife. 

Not:

I met with John the other day and tomorrow I will meet with his wife. 

Initial capital letters when referring to CERN Member States (likewise Associate Member State, Observer, etc.)