Editing 1st Marine Expeditionary Force (section)

===Transporter trace===
By the 24th century, it was common practice to store a "transporter trace" (a stored copy of a subject's molecular pattern as scanned during a normal transporter cycle).  While it is usually kept for security purposes, in extreme situations the transporter could be modified to use an older trace pattern in place of the latest scan for the purpose of re-configuring the matter stream during molecular conversion, effectively replacing a subject with a younger version of itself during matter re-construction. This technique was first used to restore Captain Jean-Luc Picard after an unsuccessful attempt by an alien energy being to merge with him. (TNG|Lonely Among Us) 

When necessary, a person's DNA could be used to create a transporter trace.  This technique was utilized by Chief Miles O'Brien and Lieutenant Geordi La Forge during a mission to the Darwin Genetic Research Station in 2365. 

The transporter trace itself would be stored for the duration of the person's tour of duty; when that person was reassigned, his or her trace would be deleted.(TNG|Unnatural Selection)

When comparing the transporter ID traces of Deanna Troi, Data and Miles O'Brien before and after they were taken over by Ux-Mal criminals, Doctor Crusher was able to detect that their nervous systems were generating high levels of synapse|synaptic and anionic energy. (TNG|Power Play)