The Producers Guild of America has achieved a milestone in its push to get its Producers’ Mark certification into film credits with a trio of majors onboard — Fox, Sony and Universal.

Use of the mark in film credits — a lower-case “p.g.a.” after a certified producer’s name — will remain a voluntary process for producers who work on pics distribbed by the three studios. Nor does it limit their ability to grant producer credits even to those who do not qualify for the PGA certification.

Still, PGA brass cited the agreements with Fox, Sony and U as a crucial step in efforts to combat the proliferation of producer credits. The fanfare for the agreements with the three studios is clearly an attempt to put some pressure on the other majors to acknowledge the mark.

“This is a remarkable moment in the entertainment industry and a historic step forward in our 12-year-long campaign at the Producers Guild to protect producers and the ‘Produced by’ credit,” said PGA prexy Mark Gordon. “Simply put, the Producers’ Mark certification changes the process of how we credit producers on a film by appropriately acknowledging producers for the actual work they have done.”

The mark has been used in five indie films for 11 producers so far, starting with Weinstein Co.’s Prohibition drama “Lawless” when it screened May 19 at Cannes, followed by Mira Nair’s “The Reluctant Fundamentalist,” which opened the Venice Film Festival; David O. Russell’s “Silver Linings Playbook”; comedy-drama “Lonely Boy”; and Rob Reiner drama “The Magic of Belle Isle.”

TWC and DreamWorks Animation have also signed on to use the mark. The latter’s “Rise of the Guardians,” which opens Nov. 21, carries the certification for producers Christina Steinberg and Nancy Bernstein.

The PGA, which has more than 5,000 members, unveiled the producers mark concept in October 2010. More than 150 notable producers endorsed the mark at that point as a way to protect the integrity of the role of the producer on a feature film.

To receive the mark, a producer’s work on a film must be vetted and certified through the PGA’s arbitration process.

“I applaud our industry partners at Universal, Sony and Fox for working with us to create this groundbreaking agreement,” Gordon said. “I would also like to thank DreamWorks Animation, the Weinstein Co. and our sister guilds — DGA, SAG-AFTRA and WGA — who have supported this from the beginning.”

The announcement noted that a producer does not have to be a member of the PGA to be eligible to receive the certification and that it is given only to producers who request it and who have been certified through the PGA’s arbitration process. That process is comparable to its arbitration process during awards season, but with quicker turnaround time, the PGA promised, once studios provide a “notice of producing credits” to the PGA when post-production on a pic begins.

The PGA’s Code of Credits spells out the qualifications for those eligible to receive the “produced by” credit for features and executive producer credit for TV. The code attaches specific weights to producer functions — 35% for development, 20% for pre-production, 20% for production and 25% for post-production and marketing — and includes job descriptions, guidelines and rules intended to help resolve credit disputes and protect the integrity of the “produced by” credit in features and exec producer credit in TV. The PGA code requires that a person must have had substantial involvement adding up to a majority of those functions to qualify for the PGA credit.

There are no immediate plans for the Producers’ Mark program to be expanded to TV and new-media productions.

The PGA emphasized that the mark does not govern who can receive a “produced by” credit on a pic.

“Studios and distributors remain free to assign the credit to whomever they wish,” the PGA said. “As requesting the mark is purely voluntary, an uncertified credit will not be understood to denote that the credited producer did not perform a majority of the work.”

The PGA also noted that the mark does not confer any specific level of compensation to those who receive it. And the certification process is not retroactive unless both the producers and studio agree to submit a notice of producing credits to the PGA.

The PGA has made reining in the volume of producer credits its signature issue since the 1998 Oscar ceremony, where five producers were credited for best-picture winner “Shakespeare in Love.” The org held its first credit arbitrations in 2001, promulgated a Code of Credits in 2004 and gained traction in 2005 when the Academy of Motion Picture Arts & Sciences announced that the PGA’s credit determination process would be the one it uses as a guideline on best picture nominations. It has also become the go-to org for credits determination for the Hollywood Foreign Press Assn., along with TV nominees for the Emmys.