(57) A security document (20,21) is provided with limited areas (17;26,27,28) of pressure-sensitive
material the surfaces of which are substantially co-planar with the remainder of the
area (25;33,34,35) of the document and the whole area of the document is overlain
with a transparent protective cover layer (18;24) so that markings can be applied
to the said limited areas (17;26,27,28) and these marks can be neither erased nor
removed from the document.
The transparent cover layer (18;24) may be adhesively bonded plastics material or
may be a coating applied in a liquid form which subsequently sets, cures or hardens.
The limited areas of pressure-sensitive material (17,26,27,28) are made co-planar
with the remainder of the document (25;33,34,35) by applying an entirely covering
layer of pressure-sensitive material which is subsequently desensitised in the areas
(25;33,34,35) where the pressure-sensitive marking is not required.
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