<timestamp>

A <timestamp> must have one of the Java-recognized formats for date and time strings.

Examples:

"3/11/13 1:32 PM"
"Mar 11, 2013 1:32:38 PM"
"March 11, 2013 1:32:38 PM PST"
"Saturday, March 13, 2013 1:32:38 PM PST"