Cooling system having a closed cooling-channel system which is formed between a main inlet and a main outlet (211, 212) for a cooling medium and comprises at least one cooling-channel section, wherein the cooling system is formed from two or more adjacent single-module elements (210.1, 210.2, 210.3, 210.x) and each single-module element (210.1, 210.2, 210.3, 210.x) comprises in each case at least one sub-portion (225.a, 225.b, 225.c, 225.x) of the at least one cooling-channel section, and wherein, in an in particular releasable connecting region of two single-module elements (210.1, 210.2, 210.3, 210.x) with respect to one another, their respective comprised at least one sub-portions (225.a, 225.b, 225.c, 225.x) adjoin in a progressive manner with respect to the at least one cooling-channel section, wherein the adjacent single-module elements (210.1, 210.2, 210.3, 210.x) have in the connecting region in each case one complementary element (361, 362) of a common media coupling, in particular in the form of a closure coupling, in the case of which, with a released connection between two adjacent single-module elements (210.1, 210.2, 210.3, 210.x), the respective sub-portion (225.a, 225.b, 225.c, 225.x) contained in a single-module element (210.1, 210.2, 210.3, 210.x), at least in its connecting region, is closed off in a media-tight manner and, with a coupled connection between two adjacent single-module elements (210.1, 210.2, 210.3, 210.x), a passage for a cooling-medium flow within the media coupling is open in the connecting region, characterized in that the cooling system is in the form of a main cooling module which comprises the at least one cooling-channel section as a base cooling-channel system, wherein the base cooling-channel system has at least two auxiliary connections (241, 242) by means of which the base cooling-channel system is able to be extended beyond the main cooling module by way of a releasable connection to at least one cooling path of an external cooling device, in that the at least two auxiliary connections (241, 242) comprise in each case one throughflow valve for the cooling medium, wherein the throughflow valve is configured such that, in a first actuation position, it opens the base cooling-channel system for a cooling-medium flow and, in a second actuation position, it closes off the base cooling-channel system in a media-tight manner, in that the throughflow valves of the auxiliary connections (241, 242) have in each case one connection region for in particular releasable connection of the base cooling-channel system to a cooling path of an external cooling device, wherein the respective connection region is in the form of a complementary element (361, 362) of a common media coupling with respect to the external cooling device, in particular in the form of a closure coupling, in the case of which, with a coupled connection between the main cooling module and the external cooling device, the first actuation position is able to be assumed and, with a released connection between the main cooling module and the cooling device, the second actuation position is able to be assumed, wherein the first and second actuation positions (I, II) are determined by a spring force, a magnetic force or an electrical force in a manner dependent on a coupling state with respect to the complementary element (361, 362) of an external cooling device. cooling system is in the form of a main cooling module which comprises the at least one cooling-channel section as a base cooling-channel system, wherein the base cooling-channel system has at least two auxiliary connections (241, 242) by means of which the base cooling-channel system is able to be extended beyond the main cooling module by way of a releasable connection to at least one cooling path of an external cooling device, in that the at least two auxiliary connections (241, 242) comprise in each case one throughflow valve for the cooling medium, wherein the throughflow valve is configured such that, in a first actuation position, it opens the base cooling-channel system for a cooling-medium flow and, in a second actuation position, it closes off the base cooling-channel system in a media-tight manner, in that the throughflow valves of the auxiliary connections (241, 242) have in each case one connection region for in particular releasable connection of the base cooling-channel system to a cooling path of an external cooling device, wherein the respective connection region is in the form of a complementary element (361, 362) of a common media coupling with respect to the external cooling device, in particular in the form of a closure coupling, in the case of which, with a coupled connection between the main cooling module and the external cooling device, the first actuation position is able to be assumed and, with a released connection between the main cooling module and the cooling device, the second actuation position is able to be assumed, wherein the first and second actuation positions (I, II) are determined by a spring force, a magnetic force or an electrical force in a manner dependent on a coupling state with respect to the complementary element (361, 362) of an external cooling device.