Video report by ITV News Business Editor Joel Hills

Question: when is a "performance review" not a performance review? Answer: when it's a "Service Delivery Standards Assessment".

ITV News has seen a copy of the food delivery company's own "crib-sheet," apparently designed to drill people within the company in the correct use of language to describe Deliveroo's riders and its relationship with them.

The Rider Vocabulary Guidelines offers a list of "dos and don'ts".

Riders are always "riders" and never "drivers" or "employees" or "workers" or "staff".

Riders are not "employed by Deliveroo to complete deliveries", they "engage with Deliveroo as independent suppliers to perform services".

Riders have "supplier agreements" not "employment contracts" and wear "kit" or "branded clothing" not "uniform".

Riders wear 'kit' or 'branded clothing' not 'uniform'. Credit: ITV News

On no account does Deliveroo "schedule shifts" instead "riders indicate their availability".

If riders want time off, they don't "book a holiday" or "request absence", they "notify of unavailability".

Reading the document, it appears at times as if Deliveroo has invented a language of its own.

Riders 'request absence' or 'notify of unavailability', they do not 'book holiday'. Credit: ITV News

The phrase "as a senior driver we would like to promote you to Driver trainer" is translated as "as a competent independent supplier we would like to make safety assessment and app demonstration work available to you".

Why the need for Rider Vocabulary Guidelines?

We asked the founder, Will Shu, who was launching new kitchen spaces for suppliers to hire on Wednesday.

Deliveroo founder Will Shu. Credit: ITV News

"I'm unaware of this document. I haven't seen it in person," Shu told ITV News.

In a statement, the company later clarified that the document has existed in various forms since 2014.

"We have almost 1,000 full time staff and with with over 15,000 riders in the UK.

"We ensure that employees know how to work with our partners, which includes training and guidelines to follow when talking to customers, restaurants, and of course self-employed riders."

The language in the document is formal, awkward and unfamiliar.

It also emphasises the distant nature of the relationship between the company and its riders who are self-employed, and this is something that matters greatly to the company.

Deliveroo has just celebrated it's fourth birthday. In a short period of time the company has proved an extraordinary success, expanding from an Italian restaurant on the Fulham Road in London to 90 cities in the UK and 12 countries.

Chefs prepare food for delivery. Credit: ITV News

The founder Will Shu attributes success to the cleverness of Deliveroo's technology - the company's website connects those hungry for a takeaway with restaurants who will put one together and also promises "great food in 30 minutes".

But the self-employed status of the Deliveroo riders has also played a part in the company's rapid progress, enabling the company to assemble a fleet (technically a "don't" according to Deliveroo's guidelines, although no alternative noun is offered) of 15,000 riders while avoiding the costs of traditional worker benefits like holiday pay, sick pay and pension contributions.

Deliveroo also doesn't have to guarantee its riders the National Living Wage or pay national insurance.

Deliveroo's business model has many critics, notably MPs, some of whom have accused the company of stretching employment law to breaking point.

A group of 20 Deliveroo riders are planning legal action against the company.

They argue they are in fact employees and are seeking compensation and enhanced employment rights.

The riders' claim will be heard by an employment tribunal and is being brought by the legal firm Leigh Day which says it has been contacted by more than 200 riders.

Last year Leigh Day successfully won a similar case against Uber although Uber is in the process of appealing the judgement.

Meanwhile, in a separate case, the Independent Workers of Great Britain is asking the Central Arbitration Committee to establish whether Deliveroo riders are workers or independent contractors.

The company has gone to great lengths to avoid these legal disputes.

Until recently Deliveroo insisted riders sign a contract containing a clause which specifically signed away their right to contest their employment status at employment tribunal.

Deliveroo has since admitted that clause 2.2 was unenforceable - begging the question why it was inserted in the first place - and has pledged to remove it.