| (57) The invention relates to a method for establishing whether or not a first person
who has identified himself for entrance to a confined space or area with the aid of
a magnetic card inserted in a card reader (7) shall be granted free passage to the
confined area through a door, gate or like entrance. The card reader (7) evaluates
a code significant to the magnetic card and, through the intermediary of electric
and/ or electronic circuits compares the code with a plurality of pre-stored codes
(12) and causes a signal to be generated for deactivating a circuit (2) for latching
the door, gate or like entrance when, and only when, acceptable agreement is found
between the sensed magnetic card code and the pre- stored codes, to therewith afford
free passage to said person. The method is mainly characterized in that:
a) A second person responsible for monitoring the persons desiring entrance to the
confined space or area activates (6) means (16) incorporated in the electric and/or
electronic circuit so that a code significant of a magnetic card subsequently sensed
in the card reader (7) can be stored among a number of pre-stored codes (12);
b) The second person identifies the first person and establishes the validity of a
magnetic card in the possession of the first person, the magnetic card being intended
for other main purposes than that of obtaining entrance to the confined space or area;
c) The magnetic card belonging to the first person is inserted into the card reader
(7) which senses the code significant to the card;
d) The significant code is therewith stored as an additional code among pre-stored
codes (12), and in that
e) a subsequent sensing of the magnetic card in the card reader (7) affords free access
to the confined space or area.
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