Flexible marking of recording data by a recording unit

A recording unit for recording an event, comprising:

• a data acquisition device for obtaining recording data representing the content of the event;
• a data storage device for storing data, wherein the stored data includes the recording data;
• a control interface device for enabling a user to control operation of the recording unit, the control interface device further comprising marking means for enabling the user to specify multiple types of non-contemporaneous marks;
• a system controller that causes, in response to the specification of a non-contemporaneous mark and a time value relative to the marking time of the non-contemporaneous mark specified by the user, the data storage device to store marking data associating the non-contemporaneous mark with the recording data obtained at a marked time relative to the marking time by the specified time value;
• wherein the marking data defines a confidence level that represents the certainty of the user that the marked time associated with the marked recording data is a time associated with the recording data that the user desires to mark and the confidence level is associated with the specified time value relative to the marking time.