This section is from the "Version Control with Subversion" book, by Ben Collins-Sussman, Brian W. Fitzpatrick and C. Michael Pilato. Also available from Amazon: Version Control with Subversion.
svn:author
If present, contains the authenticated username of the person who created the revision. (If not present, then the revision was committed anonymously.)
svn:date
Contains the UTC time the revision was created, in ISO 8601 format. The value comes from the server machine's clock, not the client's.
svn:log
Contains the log message describing the revision.
svn:autoversioned
If present, the revision was created via the autoversioning feature. See the section called “Autoversioning”.