The efforts of Internet service providers to keep track of what their customers do online poses an interesting question for the makers of anti-spyware software: Should they find a way to help users block these systems from monitoring their surfing or showing them advertising that relates to their interests?

The Anti-Spyware Coalition is setting up a project to help address those issues. It’s potentially an important step because the coalition, run by the Center for Democracy and Technology, has created standards used by the major vendors of anti-virus and anti-spyware technology to help define how dangerous certain software and cookies are.

Most anti-spyware programs scan users’ computers and sort the findings into high-, medium- or low-risk threats. Users can define their own settings to tell the programs how to deal with various sorts of threats and potential privacy invasions.

Companies in the advertising business work hard to make sure their efforts aren’t blocked by this software, sometimes resorting to lawsuits. The Anti-Spyware Coalition was formed, in part, to give the software vendors a neutral forum to define standards and help protect themselves from these suits.

The BBC surveyed several of the leading anti-spyware software companies, and most said they were still evaluating the situation. Phorm, an advertising technology company that is starting to work with the big Internet providers in Britian, has been reaching out to the software makers. Phorm is trying to make the case that its products aren’t spyware and that users are given a clear opportunity to opt out.

Phorm should understand these issues. The company, then known as 121 Media, made software that displayed pop-up ads on people’s computers after they downloaded it. It was seen as spyware by many because of questions about how well it disclosed what it would do in advance. Moreover, some versions used software known as a rootkit to make it very difficult to uninstall.

Ari Schwartz, a vice president of the technology center, said that the I.S.P. monitoring programs have created new issues that require the coalition’s guidelines to be adjusted. The questions include what sort of disclosures are made to users, what sort of data is collected and how intrusive the resulting advertising is.

Even if a software company decides that one of these I.S.P. monitoring programs violates the anti-spyware guidelines, it’s not clear how much they could block it. After all, the essence of these monitoring schemes is that they use their connection with the Internet provider to observe people from a perch in the network — they don’t have to rely on software downloads or ephemeral cookies.

Still, the I.S.P. monitoring programs do use cookies for various reasons. They all set a cookie that helps them communicate with advertising networks about what sort of ads to show each user. And Phorm, actually appends some of its information to every other cookie on a user’s computer. So while anti-spyware software couldn’t block these systems from watching users, it could at least cause trouble for them by removing their cookies. If that became widespread, Phorm and its competitors could certainly look to create versions of their technology that are not so dependent on cookies.

All this puts even more pressure on the Anti-Spyware Coalition, the Internet providers, the monitoring companies and other interested parties to look closely at these programs and try to reach a consensus about much Internet providers should be able to observe about their customers, what choices they give, and how they use the information.

If there isn’t agreement, the anti-spyware companies may well open another front in what I’ve been calling the mother of all privacy battles.