A lock cylinder comprising: - a cylinder housing; - a cylinder core which is rotatably supported in the cylinder housing about a cylinder axis and which has a keyway, extending in parallel with the cylinder axis into the cylinder core, for the key shaft of a key associated with the lock cylinder, wherein the keyway has an elongate cross-section having two narrow sides which are opposite one another with respect to a first transverse direction, and having two broad sides which are opposite one another with respect to a second transverse direction; - and a plurality of tumblers which partly project into the keyway and which are configured to block the cylinder core in a normal position of the cylinder core against a rotation out of the normal position if they are not arranged, in particular by the associated key, in a configuration releasing the cylinder core, wherein the lock cylinder comprises a coding element and the cylinder core has a receiver for the coding element, said receiver extending transversely to the cylinder axis into the cylinder core and partly overlapping with the keyway, wherein the coding element is configured, when it is inserted into the receiver, to engage into the keyway with an abutment section at one of the two narrow sides in order to form an abutment for limiting the introduction of the key shaft of the associated key into the keyway to a correct introduction depth, wherein the coding element has two coding sections (33, 33') and is configured, when it is inserted into the receiver, to engage into the keyway with one of the coding sections (33, 33') at the one of the two broad sides and with the other of the coding sections (33, 33') at the other of the two broad sides in order to encode a permitted profiling of the key shaft, and wherein the coding element is formed with mirror symmetry. - a cylinder housing; - a cylinder core which is rotatably supported in the cylinder housing about a cylinder axis and which has a keyway, extending in parallel with the cylinder axis into the cylinder core, for the key shaft of a key associated with the lock cylinder, wherein the keyway has an elongate cross-section having two narrow sides which are opposite one another with respect to a first transverse direction, and having two broad sides which are opposite one another with respect to a second transverse direction; - and a plurality of tumblers which partly project into the keyway and which are configured to block the cylinder core in a normal position of the cylinder core against a rotation out of the normal position if they are not arranged, in particular by the associated key, in a configuration releasing the cylinder core, wherein the lock cylinder comprises a coding element and the cylinder core has a receiver for the coding element, said receiver extending transversely to the cylinder axis into the cylinder core and partly overlapping with the keyway, wherein the coding element is configured, when it is inserted into the receiver, to engage into the keyway with an abutment section at one of the two narrow sides in order to form an abutment for limiting the introduction of the key shaft of the associated key into the keyway to a correct introduction depth, wherein the coding element has two coding sections (33, 33') and is configured, when it is inserted into the receiver, to engage into the keyway with one of the coding sections (33, 33') at the one of the two broad sides and with the other of the coding sections (33, 33') at the other of the two broad sides in order to encode a permitted profiling of the key shaft, and wherein the coding element is formed with mirror symmetry.