UPDATE 12/04/07: See this Microsoft KB (http://support.microsoft.com/kb/923589) for related information.

Actually, it turns out it is, but tricksy MOSS had to make it difficult.

My customer does some development work on his MOSS site over the weekend.  It’s a bit of a jumble as to what he actually did, but the end result is this:

• He tries to add a site column called "Quantity" and MOSS replies: "The column name that you entered is already in use or reserved.  Choose another name."
• He attempts to add it to another environment and that works.  Therefore, "Quantity" is not a reserved name.
• He tries to find an existing site column named "Quantity" in that site collection.  He cannot find it.

I did some research,  and even some coding, waxed philosophical and finally found that a column named Quantity did, in fact, exist.  It was in the "_Hidden" group.  Hence, we could not find it via the SharePoint user interface.

How did it get there?  I do not know, but I have a theory (or as my wife would call it, "blah blah blah").  Somewhere along the line, a fabulous forty template was added and probably activated at a site in the site collection.  It was then deactivated (or the site removed).  The site column, however, remained but in the "_Hidden" group.  If someone knows better, please let me know via email or post in the comments.

SharePoint was telling the truth.  It’s hardly worth pointing out that that message is not as helpful as it could be.  It would be nice to see that message fork into two different messages in the future: 1) Say that the column name is reserved or it is not. 2) If it’s not reserved, show the site, or at least the group, where the column name is already used.

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