XMLDB Editor and Reserved Names
One (of the many) good reasons to use the XMLDB editor in Moodle rather than hacking the
db/install.xml file directly is that it warns you if you use a reserved name.
The red Reserved text after
[XML] in the screenshot is indicating that the word
column is reserved and shouldn’t be used. It would be nice if it stopped you from saving such a change (it doesn't) but at least it indicates a problem.