I was faced problem with column name “doctype”, I was not able to create “doctype” column with any of the data type into SharePoint List, and I was getting “Unknown error” into my page when I tried to create column. I tried to find the solution on the internet for some time, but I didn’t get good information, I believe that “doctype” column name is reserved for internal purpose, so we can’t use same name like ID, title column name.
Luckily I was able to create “doctype” as single line of text data type, now the actual problem started, I was not able to delete “doctype” column from SharePoint list, definitely we can write custom code and delete same column from code. But I have found easy way to delete “doctype” column from going to tool called “SharePoint Manager 2007” and I have selected my site-> list -> “doctype” column and delete from that tool. You can find more information regarding SharePoint manager 2007 from my blog, here is link http://sanketinfo.wordpress.com/2008/10/15/sharepoint-manager-2007-%e2%80%93-administration-tool/
Now if we have requirements to create “doctype” into list, then we can create same column name by changing character case. “doctype” column name is case-sensitive, like we can create column with named “DocType”
