Different missions provide time information in a variety of ways.
There are two ways to handle this diversity in time information. Another approach is to store the time as close as possible to the original reference frame chosen by each mission. In addition, if information is not available to compute an absolute time, is still possible to perform some timing analyses on the data set. The disadvantage, in this latter approch, comes in combining data from different missions, for it can be time consuming to understand the reference time convention and to adjust it to a common time frame. This allows the analysis software can make the conversion.