If you ever want to stick a square yellow or green "O" on a T-shirt or a coffee mug, you better check with the University of Oregon first because the school has registered it as a trademark.

The styled block letter has become the latest of nearly two dozen officially licensed university symbols under legal protection."It's more a protection against what might happen, not what has happened already," said Muriel Jackson, who as assistant vice president for administration oversees the dispensing of the university's good name.

Anybody who tries to enhance merchandise by attaching a university "O" without the school's permission could be charged with trademark infringement.

The lightest penalty would be a letter from Jackson, who would advise the merchant that the "O" is protected and is not to be used without written permission or without paying the university a 6 percent fee on the wholesale income.

She said that most manufacturers are reputable and are well aware of the legal squabbles in the late 1970s when universities fought to prevent exploitation of their images.

"But there are occasional problems with cottage industries, and in this age of T-shirts you can't be too careful," she said.