Subscribers to a nationwide computer network contend the owners are taking a byte out of the First Amendment by censoring the network's electronic bulletin board messages.

But officials for the Prodigy network, which provides consumer and information services to several hundred thousand subscribers, maintain they have the same right as newspaper and broadcast executives to "set boundaries" on the exercise of free expression.An electronic communications law expert agreed, saying the challenge for Prodigy is enforcing standards tough enough to avoid lawsuits sparked by bulletin board content.

"They should be able to forbid whatever they forbade in their subscriber agreement," Dallas attorney Benjamin Wright said recently.

But subscriber indignation has been flowing for weeks into the electronic bulletin board Prodigy sets aside for complaints.

"Censorship is the most un-American, communist thing in the Prodigy service," wrote subscriber Chris Hanke, who did not say where he lives. "If a member finds anything offensive (on the bulletin boards) this service should ask them if they still want to be a member of this service."

Subscriber John Gillis likened the service's editors to "old ladies" afraid of mice. That drew a one-word retort from Ray Bandel, one of the badly outnumbered subscribers who support Prodigy's standards: "Bull."

Prodigy, which carries such items as stock quotes, advertising and horoscopes, considers itself a "family service," company spokeswoman Martha Griffin said. It is jointly owned by Sears and IBM Corp.

"When you send something into a public bulletin board on a family service, then you expect to write within the boundaries of the rules that are stated," she said from her White Plains, N.Y., office.

When they join, Prodigy subscribers agree to refrain from sending messages that contain profanity or obscenity, threaten or insult, might offend those doing business through Prodigy, or are "otherwise objectionable."

Messages rejected by Prodigy editors included one seeking the least painful way to commit suicide and another accusing somebody of being an embezzler, said Geoffrey Moore, who directs market programs and communications for Prodigy.

"The Constitution bestows no rights on readers to have their views published in someone else's private medium," Moore wrote in a Dec. 16 essay in The New York Times. "What the Constitution does give readers is the right to become publishers themselves."

But some subscribers contend the service is heavy-handed and goes beyond its own standards. Daniel Hunter wrote that Prodigy has rejected his messages to the Arts Club bulletin board because they made reference to the Marquis de Sade and contained "a historical discussion of mass murders, plagues, etc."

"If anything, our editors do err on the side of conservatism," Ms. Griffin said. "There are other bulletin board services where people can express more extreme views if they wish."

She also said Prodigy does not interfere with private messages sent directly from one subscriber to another. "The only way we would see those messages is if the receiver complained about their content," she said.

Wright said the real issue for Prodigy and other computer networks "is the extent to which a video-text service provider has an obligation to look at what's getting on the bulletin boards."

He noted that Soldier of Fortune magazine recently was successfully sued by the family of a man slain by a killer-for-hire who had advertised in the magazine.

"The law found that the magazine had a duty to screen the information it published," he said.

Prodigy may not have as great a duty, Wright said. That would depend on whether a judge or jury found it to be "more like a newspaper or magazine, which have a greater duty to monitor content than entities not in that business."