— Stephany Folsom (@StephanyFolsom) September 11, 2017

There's something very wrong when a major corporation is doing more to protect your interests than your own guild. — Stephany Folsom (@StephanyFolsom) September 11, 2017

What Marvel presumably "gave" Folsom was inclusion in the Notice of Tentative Writing Credits, or NTWC, that Marvel would have sent to each writer and the WGA itself. Those credits would then have become final, but one or more writers presumably protested the credits, resulting in an arbitration. The credits in at least one version of the poster are “Story by Craig Kyle & Christopher Yost and Eric Pearson” — the “&” signals a writing team, while the “and” denotes writers who wrote independently — and “Screenplay by Eric Pearson.”

Folsom came on to the project in December 2015, after Kyle & Yost. She was best known at the time for a 2013 Black List script, 1969: A Space Odyssey or How Kubrick Learned to Stop Worrying and Land on the Moon, an alternate-history story of a publicist who convinces filmmaker Stanley Kubrick to work with NASA in order to fake the moon landing.

Credits matter, because they indicate who made the most significant contributions to a script (at least usually), signal professional stature and determine whether a writer receives residuals and sometimes bonuses as well.

In order to heighten the importance of credit, and reduce the perception that screenwriters can be swapped in and out like sparkplugs, the WGA’s own members have adopted rules that limit “Story by” screen credit to two writers or teams, and that guarantee at least shared "Story by" credit to the first writer or team (Kyle & Yost) on an original screenplay.

That probably left Folsom and Pearson battling for a “Story by” slot. With Pearson receiving sole Screenplay credit, it would perhaps have been hard for the arbitrators (who are themselves experienced screenwriters) to conclude that he didn’t deserve a “Story by” credit as well.

The WGA and the four writers did not respond to requests for comment, while Marvel declined to comment.

In any event, Folsom’s tweets triggered a calming reply from Christopher McQuarrie — maintaining a good relationship with Marvel is “just as important as a credit,” he wrote — and dozens of saddened and outraged responses from apparent fans and writers, several of whom urged Folsom to quit the guild.

Although Folsom described her Marvel relationship in a tweet as being “as good as any corporate relationship can be,” that wasn’t the picture just two months ago, when Marvel issued a poster with writing credits — but without Folsom’s name. Her tweet then excoriated the company, not the WGA:

It's gross that Marvel issued a poster and trailer for THOR with full credits, when writing credits haven't even been determined yet. — Stephany Folsom (@StephanyFolsom) July 23, 2017

“Gross” or not, it is permitted: WGA rules say that “prior to the final determination of screen credits … the work of participants not receiving screen credit may be publicized by the Company.”

And that apparent back and forth by Marvel hints at why the guild in its early years fought ferociously for the right to determine credit, in order to prevent studio practices that at one time involved gratuitously doling out writing credit to moguls’ paramours or favored writers. The studios soon saw the advantage of letting the guild have the final say, since that meant that disappointed writers’ fury would be more often turned on their own union.

A source told The Hollywood Reporter that Folsom is appealing the decision. That will trigger a review by a so-called Policy Review Board — a second panel of writers — but a PRB is only supposed to look for rule violations, not re-judge the whole case. (Full disclosure: This reporter was an associate counsel at the WGA in the early 1990s and served as advisory counsel to several PRBs.)

Absent an unexpected thunderbolt from the sky, the WGA’s hammer has dropped and its judgment is likely to remain unchanged.