BACKGROUND OF THE INVENTION 
     The invention relates to a communication system having at least one mobile communication device. 
     Communication systems of this generic type that can move their location are known. They have at least one mobile communication device, by means of which an action of further devices communicating with the communication device can be tripped. For instance via a remote controller of the communication device, various pieces of equipment and/or devices can be actuated within a usage area. Typical usage areas are for instance a building with multiple spaces, where different pieces of equipment can be actuated inside the spaces by means of the communication device. Since when remote controllers are used the radio waves have the property of penetrating both the boundary walls of the individual spaces and objects, the communication device necessarily has to be designed in such a way as to enable operating only one particular piece of equipment, without tripping other devices in other spaces that are also actuatable with the communication device. To that end, it is known to provide the communication device with a corresponding number of actuating means, so that each possible control function within the operational range can be executed separately, or so that some control functions can be projected onto a combination of actuating means, or a chronological succession of actuating means. 
     SUMMARY OF THE INVENTION 
     The communication system of the invention that can be moved from place to place, offers the advantage that in a simple way, a spatially dependent multiple use of actuating means of the communication device is possible. Because within one usage area of the at least one communication device, position marks are assigned to defined regions which position marks, upon entry of the communication device into the defined region of the communication device impart the actual position, an automatic switchover of the communication device, and in particular the setting of the at least one actuating means, can be switched over to tripping of an action of a device located in the current defined region. Thus by means of one actuating means, many different devices can be actuated; this substantially improves the ease of use of the communication device. 
     In a preferred feature of the invention, the position marks generate electromagnetic waves, which are received by the piece of communication equipment; position marks belonging to one usage area broadcast different electromagnetic waves per defined region, so that an unambiguous association with a defined region is possible. By way of the electromagnetic waves received from the communication device, an association with the defined region can be made, and internally in the communication device a switchover of the setting of the actuating means can be done. 
     In a further preferred feature of the invention, it is provided that the position marks are activatable by the communication device. As a result, it is highly advantageously attained that the position marks issue a position signal to the communication device only whenever the communication device enters the defined region associated with the active position marks. Thus all the position marks within the usage area are in readiness and are activated only whenever the communication device enters their region. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described in further detail below in an exemplary embodiment in conjunction with the associated drawing, which schematically shows a usage area of a communication device. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the drawing, a usage area marked  10  of a communication device  12  is shown. The usage area  10  for instance includes a building or part of a building  14  with individual spaces  16 ,  18 ,  20 ,  22 , and  24 . A communication space need not be identical with the dividing up of the building into rooms. For instance, one communication space can encompass several rooms. Naturally any other constellation of the usage area  10  is also conceivable. In the exemplary embodiment, it is assumed that a communication device  12  is assigned to the usage area  10 . Naturally entirely analogously, a plurality of communication devices  12  can also be assigned to the usage area  10 . 
     In each of the spaces  16  through  24 , at least one piece of equipment  26 ,  28 ,  30 ,  32 , and  34  is installed that is actuatable by means of the communication device  12 . To that end, the communication device  12  for instance has a radio transmitter while the pieces of equipment  26  through  24  have a corresponding radio receiver. The pieces of equipment  26  through  24  can for instance be drive mechanisms for rolling window shutters, remote-controllable pieces of consumer electronics equipment, video cameras, or any other arbitrary piece of equipment that is actuatable by means of a remote controller. 
     The spaces  16  through  24  form defined regions of the usage area  10 . Each of the spaces  16  through  24  is assigned one position mark  36 ,  38 ,  40 ,  42 , and  44 , respectively. 
     The position marks  36  through  44  have an energy source or are connected to an energy source, and they include devices for generating electromagnetic signals. The electromagnetic signals can be produced for instance by triggering a coil with a supply voltage of defined frequency. The position marks  36  through  44  are designed such that each of the position marks  36  through  44  broadcasts different electromagnetic signals, and in particular electromagnetic signals of different frequency. 
     The communication device  12  has a receiver  48  for the electromagnetic signals broadcast by the position marks  36  through  44 . The position marks  36  through  44  are designed such that the broadcast electromagnetic signals can be received only within a narrowly defined spatial range of the receiving unit  48 . In particular, the position marks  36  through  44  are designed such that reception of the electromagnetic signals is possible only when moving directly past the position marks  36  through  44 . For example, the position marks  36  through  44  can be disposed in the region of access doors to the spaces  16  through  24 , so that when a person possessing the communication device  12  moves past the applicable door, the receiving unit  48  receives the electromagnetic signals transmitted by the position mark  36  through  34  that has just been passed. By means of the electromagnetic signals received, an actuating means  50  of the communication device  12  is varied in terms of a function setting. 
     The function setting of the actuating means  50  is designed such that when one of the spaces  16  through  24  is entered, the piece of equipment  26  through  34  located in this space can be actuated. For instance, if the communication device  12  is moved into the room  20 , then the receiving unit  48  receives a signal from the position mark  40  that adjusts the setting of the actuating means  50  to control of the piece of equipment  30 . If the communication device  12  then moves on into the space  18 , the receiving unit  48  receives the electromagnetic signals of the position mark  38 , as a result of which the functional setting of the actuating means  50  is switched over to actuating the piece of equipment  28 . 
     Thus in summary, in a simple way by means of only a single actuating means  50 , it is possible to actuate the most various pieces of equipment  26  through  34 ; because of the switchover of the function setting, only whichever is the current piece of equipment, that is, the piece of equipment  26  through  34 , in whose defined region (spaces  16  through  24 ) the communication device  12  is located at the moment, can be actuated. It is understood that the communication device  12  may have additional actuating means which for instance accomplish an actuation of all the pieces of equipment  26  through  34 , regardless of whatever is the current position of the communication device  12 , or that are used for actuating other pieces of equipment. 
     The receiving unit  48  can for instance be embodied as a transceiver unit  48 ′, so that communication is possible with the position marks  36  through  44 , which have a corresponding receiving device. The thus-cooperating position marks  36  through  44  and the transceiver  48 ′ serve to detect any motion of the communication device  12 , so that all the position marks  36  through  44  are in a resting phase, and only the position mark  36  through  44  in whose region the communication device  12  is located at that precise time, or the communication device  12  just now entering its region, is actuated. This offers the advantage of reducing energy consumption by the entire communication system that is movable from place to place to the bare minimum necessary. 
     To enable detection of the motion of the communication device  12 , the communication device can for instance have a device  52  that trips a signal accordingly when the communication device  12  is in motion. The device  52  can be formed for instance by a ball located in a cage and made of an electrically conductive material; by motion of the communication device  12 , this ball short-circuits contacts disposed, electrically insulated from one another, inside the cage. By means of this kind of short circuit, the transceiver  48  that thereupon responds to the current position mark  36  through  34  at that precise time can be activated. 
     The electromagnetic signals broadcast by the position marks can for instance be low-frequency signals, or signals located in the frequency range of radio signals of the communication device, or high-frequency signals. By means of the low-frequency signals and the electromagnetic signals located in the frequency range of the communication device  12 , it is possible, highly advantageously, because of their spatially limited nature, to tune the actuating means  50  exactly to the precise current defined region (spaces  16  through  24 ). By means of the high-frequency signals, which have a relatively limited range, are preferably suitable for triggering the communication device  12 , because in this way electromagnetic signals of more than one position mark  36  through  44  are prevented from being superimposed on one another.
The invention relates to a communication system, having at least one mobile communication device which has at least one actuating means for tripping an action of at least one piece of equipment communicating with the communication device. It is provided that within a usage area ( 10) of the at least one communication device ( 12), defined regions ( 16, 18, 20, 22, 24) are assigned position marks ( 36, 38, 40, 42, 44), which when the communication device ( 12) enters one of the defined regions ( 16, 18, 20, 22, 24) of the communication device ( 12) impart the current position for switching over a function setting of the at least one actuating means ( 50).