In the tech world, language is usually precise. Except when it comes to telecoms firms' use of the word 'unlimited'. In Ireland, companies like Eir, Vodafone, Virgin, Three and Sky all advertise unlimited broadband or mobile services that have data limits buried in the small print. They call them 'fair use'.
All of the companies admit that some of their customers hit those limits. Some customers end up paying penalty charges.
But the operators say that the 'unlimited' claim is harmless because only a small minority of users are affected. The services are unlimited, they say, for the majority of users that do not hit the limits.
Asked by this newspaper whether they have any qualms about using the word 'unlimited' for limited services, all of the above operators contacted replied "no".
The limits, which are often only discoverable with a trawl through terms and conditions or an accompanying booklet once the product is purchased, vary considerably.
Virgin Media's mobile data limit for its unlimited data service is 40GB, a modest level. Three's equivalent limit for its unlimited data is 60GB. The same firm's limit for its unlimited home broadband is 750GB, while Eir's limit for its unlimited fibre broadband is 1,000GB.
Penalties for exceeding the limits also vary. Eir charges up to €100 per month for exceeding its limit.
This is what one customer who contacted the Irish Independent found to his annoyance.
'Michael' (his real name and address are with the editor) has a family of five and so chose Eir's unlimited fibre package.
"When my first bill arrived, I was charged €20 for excess usage," he says. "It was the first time I was aware of excess usage. I contacted Eir support and they said that a one-terabyte 'fair usage' limit was in the terms and conditions and I should have read these before signing up."
The problem is that Eir does not mention any fair usage in its unlimited broadband advertisements. Neither had the salesperson who sold the package.
Michael made the mistake of assuming that the word 'unlimited' meant what it said. So he did not think to burrow deep into the tiny terms and conditions.
"We are a family of five, including a boy of 21, and two girls of 19 and 18," says Michael.
"My son got a PlayStation 4 for Christmas and he purchased a few games online. So between him downloading these games, as well as some system updates for the console and normal browsing, I was charged for excess usage.
"The next time, I received a bill for €197, €100 more than the usual bill. Despite my best efforts to get my kids to go easy on the content they were downloading, I failed dismally and most of the bills I received after that also had a €100 excess usage charge."
Michael complained to the Advertising Standards Authority for Ireland (ASAI), arguing that there had been no proper notice of any restriction on Eir's unlimited fibre broadband and that he was being unfairly punished as a family user.
The ASAI took Eir's side. "Currently, companies are allowed to use this term when there is a fair usage policy in place, as long as the fair usage policy does not affect 99pc of customers on that plan," said an ASAI complaints investigator in correspondence seen by the Irish Independent.
Michael is not the only one affected. "I have Eir's unlimited fibre broadband but once you go over their monthly fair use policy, there is no warning," said Glen Mulcahy, an audio-visual professional.
"I asked if there was an app or alert to manage the data allowance but they said no. So, basically, there is no way to manage your bill."
A spokesperson for ComReg said that use of the word 'unlimited' by telecoms firms was an ASAI matter and was not considered legally binding in an advert.
The ASAI's code of standards claims that "a marketing communication should not mislead, or be likely to mislead, by inaccuracy, ambiguity, exaggeration, omission or otherwise". However, there are signs that the situation with regard to use of the word 'unlimited' may be changing.
"The ASAI is currently finalising a guidance note for telecommunications companies when advertising mobile and broadband services," a spokeswoman told the Irish Independent.
"In relation to the word 'unlimited', the ASAI has identified this term as one to be reconsidered and we can confirm a comprehensive review will be undertaken."
So will this mean that Eir, Vodafone, Virgin, Three and Sky will have to quickly change their advertising art? Perhaps not yet.
"This process has not formally begun yet as we have been prioritising our efforts on finalising the guidance note, so a timeline of when this will be completed cannot be given," said the ASAI spokeswoman.
"This process will include a consultation process with relevant stakeholders, as was undertaken when researching and compiling the imminent guidance note.
"Once undertaken, we will be looking at the conditions in which the term can continue to be used by advertisers."
It is possible that the organisations funding the ASAI may veto any change in the rules. After all, the term 'unlimited' sells subscriptions, even if a minority of customers end up having to pay twice when the hidden limits are breached.