England captain Eoin Morgan says there is "nothing untoward" in having coded information passed to him by the analyst during play.
A series of letters and numbers were hung from the dressing room balcony during South Africa's innings in England's 3-0 Twenty20 series win.
The information took the form of a letter and a number, for example "C3".
"It's 100% within the spirit of the game," said Morgan, adding that England will continue to use the system.
"There's no real signals. There's always been constant communication, verbal or physical, from the changing room to us on field to help improve my decisions as captain and Jos Buttler's decision as vice-captain.
"It's about maximising information that we are taking in and measuring it against coaches recommendations, the data of what's going on."
The codes were relayed to Morgan by analyst Nathan Leamon.
Former England captain Michael Vaughan criticised the approach after the tourists completed a series clean sweep on Tuesday.
Morgan said: "There weren't many decisions that varied from mine. There were three in the first game, two in the second and a couple in the third.
"We're definitely going to continue with it and give it an enough sample size to see if it makes a difference or improves our decision-making on the field or our performance."
England said during the third T20 that they had cleared the system with the match referee and anti-corruption officials.
South Africa and England begin a three-match one-day series starting on Friday in Cape Town.
England rest Archer, Stokes & Curran
Despite the ODIs forming part of the Cricket World Cup Super League, which decides qualification for the 2023 World Cup, both sides are resting key players.
England are without pace bowler Jofra Archer and all-rounders Ben Stokes and Sam Curran.
All three have spent long periods in bio-secure bubbles during England's summer and the Indian Premier League before this tour, and Morgan has spoken about the need to look after players' mental health as well as their physical condition.
South Africa pace bowler Kagiso Rabada has been ruled out by the adductor strain that meant he missed the final T20, while former captain Faf du Plessis is rested.
When are the ODIs?
The series follows an identical pattern to the Twenty20 series with day-night games (11:00 GMT) in Cape Town starting and ending the series on 4 and 9 December respectively.
The second game takes place in Paarl and gets under way at 08:00 on Sunday.
How can I follow the series?
There will be live text commentary on all the matches on the BBC Sport website.
Cricket correspondent Jonathan Agnew will provide updates on BBC Radio, with analysis from former England captains Alastair Cook and Michael Vaughan and ex-England women's batter Ebony Rainford-Brent.
There will also be Test Match Special podcasts after each game.