I've been observing a skirmish between a group of subscribers to the online music service Emusic.com and the service's management. What it brought home was how important the details are if you want to be successful.

I have written about Emusic before but let me recap: Emusic.com is an online service now owned by Vivendi Universal Net USA (VUNet USA) and Universal Music Group, a division of Vivendi Universal. The company's published terms and conditions says that, "subject to certain limitations as described herein, you are granted unlimited download rights to our catalog of MP3 music files" for a fee as low as $9.99 per month.

When Emusic first started I immediately subscribed and was ecstatic about it. My music habit has been well-fed and I have discovered artists I might never have heard of otherwise.

But a few months ago things started to change in little ways. Emusic had a cookie system that, if you enabled it, would log you into its Web site automatically whenever you visited. The cookie logon just stopped working. A small thing, perhaps, but very annoying - particularly when the site now also automatically logs you out after a few minutes.

But the biggest change happened recently: Emusic started canceling subscriptions. The company's main complaint (as outlined in a company statement I received Oct. 28) is some subscribers "do not follow the usage terms outlined in our terms and conditions. . . . Examples of violations include the sharing of passwords, use of automated systems to download massive numbers of tracks and other activity . . . in excess of what is reasonable for one's personal use. Accounts that we believe are violating the terms and spirit of the service are subject to cancellation."

Not surprisingly, the subscribers who were booted were annoyed. And with good reason: Emusic specifically said "you are granted unlimited download rights to our catalog of MP3 music files." The limitations clause doesn't carry any other volume proviso, so the term "unlimited" must mean just that.

This means that the statement's definition of a "violation" of usage terms is based on unstated behaviors and limits as deduced by Emusic. That makes it a little tricky for subscribers to stay on the right side of acceptable behavior.