WASHINGTON — The appointment of an independent arbiter, known as a special master, to filter the documents that F.B.I. agents seized last month from former President Donald J. Trump’s residence and club has heightened interest in that person’s responsibilities.

The special master, Raymond J. Dearie, is a judge on senior active status with the Federal District Court for the Eastern District of New York. A Reagan appointee, he was one of two candidates suggested for that role by lawyers for Mr. Trump, and the Justice Department said it found him acceptable.

Judge Aileen M. Cannon, a Trump appointee on the Federal District Court for the Southern District of Florida, designated Judge Dearie as the special master on Thursday and laid out the specifics of his job. Here is a closer look.

A special master is a person appointed by a judge to assist the court with its proceedings. In contrast to a standing master, who is installed to help on a continuing basis, a special master helps with a particular matter or case. Masters can hold proceedings and then make reports and recommendations, which the judges can accept or reject.

Judge Dearie is tasked with systematically examining more than 11,000 documents F.B.I. agents took from Mr. Trump’s estate, Mar-a-Lago, during a court-authorized search on Aug. 8.

As special master, Judge Dearie will oversee a process of sorting the documents, separating government records from personal material. Within each of those categories, he will identify which are protected by attorney-client or executive privilege, and which do not contain privileged material.

As envisioned in the order, Mr. Trump’s lawyers will first examine each item and propose how to categorize it. Judge Dearie will then show their list to the Justice Department. If the two sides disagree about some items, he will make a recommendation to Judge Cannon on how she should rule.

Judge Dearie is also to verify a property inventory that the F.B.I. has already produced. And if Mr. Trump’s lawyers eventually file a motion to return personal property, he is to evaluate those claims and make recommendations to Judge Cannon about them as well.

Judge Cannon imposed a deadline of Nov. 30 for the documents review.

Notably, it is unclear how much material there is to examine. While the F.B.I. has said there are about 11,000 documents, it has not indicated how many pages of material that amounts to.

There may be further complications. Because no court has ever ruled that a president, current or former, can use executive privilege to block criminal investigators from the Justice Department from gaining access to executive branch materials, Judge Dearie may need to develop a new legal analysis to evaluate any such claims.

Moreover, there may be page-by-page complexities to sort through, like if Mr. Trump has handwritten notes of his deliberative thinking on a particular sheet of an otherwise unprivileged document.

The special master has 10 days to consult with lawyers for both sides and then provide Judge Cannon with a schedule establishing a timeline for the overall review, deadlines for either side to make arguments about particular documents that may be in dispute, and then time for him to adjudicate any disagreements. Both sides will then have five days to object to his proposed calendar.

On Friday, Judge Dearie ordered lawyers for both sides to meet at the federal courthouse in Brooklyn on Tuesday afternoon. He also invited them to submit docketed letters ahead of time proposing “agenda items for discussion.”

The documents marked as classified are supposed to be up first — and they could present an immediate complication.

The order directs Judge Dearie and the two sides to prioritize processing the 100 or so documents with classification markings. Judge Cannon made that concession to the Justice Department, which had objected to her injunction blocking criminal investigators from full access to that material, saying that it is endangering national security.

Judge Cannon suggested that Judge Dearie could make an interim report about that portion of the injunction, after which she would consider adjusting it even before the full review is done. The idea seems to be to prevent her intervention from delaying the F.B.I. too severely from regaining full access to those records in its investigation.

But as the first step, Judge Cannon instructed the government to show those documents — some of which have the extremely classified markings of “top secret” and “sensitive compartmented information” — to Mr. Trump’s counsel.

The judge said this should be done under “controlled access conditions (including necessary clearance requirements).” But it remains to be seen whether anyone on Mr. Trump’s legal team has, or can obtain, a security clearance high enough to gain lawful access to such material.

Yes, the special master can have assistance for his task.

Over the objections of Mr. Trump’s legal team, Judge Cannon said that Judge Dearie may consult the National Archives in assessing the status of documents.

Her order also suggests that Judge Dearie may propose hiring “additional professionals, support staff, or expert consultants.” He must submit a plan to both parties for comments, after which Judge Cannon would consider it.

Judge Dearie may have less help in analyzing the 100 or so documents with classification markings, however. While he is exempt from the need for a security clearance because he is a judge — notably, he formerly also served on the Foreign Intelligence Surveillance Court — any clerks or assistants would need a clearance to be able to see those documents.

Mr. Trump will pay for the special master and his expenses, based on an arrangement to be determined later, Judge Cannon wrote.