An article in the New York Times (free registration required) used -coei as a suffix. Observe:
What exactly does this mean, and whence does it come? I can’t find anything on it under Google.
I suspect that what you’re seeing is screwed up text coding. Newspapers have software (often proprietary) for preparing their stories for typesetting, and such software includes codes for symbols. When the code is entered incorrectly, it shows up as text instead. I can’t imagine what the symbol might be in this case, but I’ve seen it happen before.
Hmmm, I searched through five dictionary sites and could not find your suffix.
Even AskOxford didn’t have it (If they don’t have it, it doesn’t usually exist). Your best bet may be to ask their experts about it at their site.
Based on the context, it looks like it may be a TM symbol.