A city board appeared poised Wednesday to protect the Citgo sign’s place atop the Kenmore Square skyline, in the face of potential redevelopment.

A draft report being drawn up by the Boston Landmarks Commission would restrict any new owner’s ability to make drastic changes to the shape or views of the iconic sign, which sits above a building that Boston University is selling to development firm Related Beal.

They’re still determining how high the sign — which now sits atop a six-story building — might be allowed to go should the new owners want to build taller.

Any formal landmark designation is probably still months away and would require public hearings and the approval of both Mayor Martin J. Walsh and the City Council. But the meeting Wednesday, in a hearing room in an out-of-the-way corner of City Hall, was the first clear indication of the commission’s plans.

“Ideally, we’d want nothing to change. That’s not going to happen,’’ chairwoman Lynn Smiledge said. “So how do we preserve what’s most important about the sign?’’

Commission members put together a list of “character-defining features’’ they would protect through a landmark designation, everything from its 60-foot-by-60-foot dimensions to its famous red triangle and the pattern of its lighting.

Also on the list: “unobstructed visibility’’ from Fenway Park, the Massachusetts Turnpike, Memorial Drive, and elsewhere, which probably would prevent Related from building anything next door that would be taller than the sign.

Still, some members and officials from the Boston Planning & Development Agency warned against being so restrictive that any new development would effectively be hamstrung.

“The intent isn’t to crystallize this in amber,’’ said Jon Greeley, director of development review for the BPDA. “The intent is to say, ‘This is really important to the city.’ And that’s the lens through which we’d like any changes to be viewed.’’

Greeley said Related, which has not yet closed on its purchase of 660 Beacon and several neighboring buildings, has not approached the BPDA with any plans for the site. Through a spokesperson, the developer has declined to comment on what they might have planned.

The challenge of keeping the iconic sign, for which Citgo leases space from BU, prompted some local developers to pass on the project and sparked worries that the sign might come down. A petition drive gathered more than 5,000 signatures urging the city to grant the sign landmark status.

While an effort to designate the sign a landmark failed in the early 1980s, this push appears more likely to succeed. The board Wednesday was focused mainly on the fine details of what, precisely, should be preserved.

“The crux of it is what things are you going to fix in place, and what are you going to allow flexibility on,’’ said Greg Galer, executive director of the Boston Preservation Alliance.

Tim Logan can be reached at tim.logan@globe.com. Follow him on Twitter @bytimlogan.