Here is one report (Not exactly what you asked, though.):
How did prisoner exchanges and paroles work? (U.S. Civil War: Battles and fighting forces)
Prisoner exchanges were a way for captors to avoid the responsibility
and burden of guarding, housing, feeding, clothing, and providing medical
care for POW's.
Exchange of prisoners began with informal agreements between the
commanders of the armies after particular battles, but the practice was
codified by a cartel between the USA and CSA in July 1862. The cartel was
suspended by the US in May 1863, but individual commanders again arranged
exchanges and paroles until the US called a halt to all exchanges in early
1864. When the CSA agreed to correct some irregularities in its earlier
exchanges, and when it agreed to treat captured black troops equally with
whites, the 1862 cartel was again put into operation in early 1865.
Commissioners of exchange were appointed by each government, and they
exchanged and compared lists and computed how many on each side were to be
exchanged. There were official points where prisoners were to be taken
for exchange: City Point, VA in the East and Vicksburg in the West.
Equal ranks were exchanged equally, and higher ranks could be exchanged
for some number of lower ranks according to an agreed upon list of
equivalents (e.g. 1 colonel equaled 15 privates). If one side still had
prisoners left, after the other side had exhausted its supply of prisoners
by exchange, those excess prisoners would be released on parole.
Paroled prisoners were returned to their side, but were prohibited by
an oath of honor from taking up arms or performing any duty that soldiers
normally performed (like garrison or guard duty) until they were properly
exchanged. Generally each side maintained parole camps where their
paroled soldiers were kept while they awaited exchange, but in other cases
the parolee was allowed to return home until exchanged.
[Sources: Boatner, Civil War Dictionary; Miller, ed, "Prisons and
Hospitals", vol 8, Photographic History of the Civil War]
<b><font color="gold">Ernie Sands, General
4th Brigade, Cavalry Division, XIV Corps,
Army of Cumberland, USA
ACWGC Records Site Administrator
</b></font id="gold">