The "Time Worked" field in a service record is the time spent working on it, so far. It's the sum of the times entered in the record update page. It's expressed as hours:minutes, e.g. 0:10 means 10 minutes.
When displayed in a display/update page, it is followed by how long it's been since it was updated (using the Date Time Worked field). The display is highlighted (in red) if the time between the most recent work and the time the "Time Worked" field was updated is greater than two days. Highlighting (in red) is also used when the field is is displayed in a queue listing. The assumption is that the time for that work has yet to be logged.
When specifying this field in a customized sort or display, any of the names "time_worked" or "Time Worked" can be used.