Altar Rail or Communion Rail
The railing
which guards the sanctuary and separates the latter from the body of
the church. It is also called the communion-rail as the faithful kneel
at it when receiving Holy Communion.
It is made of carved
wood, metal, marble, or other precious material; it should be about two
feet six inches high, and on the upper part from six to nine inches
wide. The "Rituale Romanum" (tit. iv, cap. ii, n. I) prescribes that a
clean white cloth be extended before those who receive Holy Communion.
This cloth is to be of fine linen, as it is solely intended as a sort
of corporal to receive the particles which may by chance fall from the
hands of the priest. It is usually fastened on the sanctuary side and
when in use is drawn over the top of the rail. It should extend the
full length of the rail, and be about two feet wide, so that the
communicant, taking it in both hands, may hold it under his chin. Its
very purpose suggests that it is not to be made of lace or netting,
although there is nothing to forbid its having a border of fine lace or
embroidery.

Instead of this cloth a gilt paten, larger than the paten
used at the altar, to which a handle may be attached, or a small gilt
or silver salver, or a pall, larger than the chalice pall, may be used.
These latter are usually passed from one communicant to the other, and
when the last at the end of the rail at the Gospel side has received
Holy Communion the altar boy carries the paten to the first
communicants at the Epistle side. A consecrated paten may never be
placed for this purpose in the hands of lay persons.[1]
[1]
Written by A.J. Schulte. Transcribed by Michael C. Tinkler. The
Catholic Encyclopedia, Volume I. Published 1907. New York: Robert
Appleton Company. Nihil Obstat, March 1, 1907. Remy Lafort, S.T.D.,
Censor. Imprimatur. +John Cardinal Farley, Archbishop of New York