1. A programmable personal medical device comprising an implantable cardiac pacemaker or implantable defibrillator comprising: a data communication interface ( 11 ), coupled with a programmable personal device wherein the programmable personal device receives data containing programming instructions via the data communication interface; a memory ( 15 ) coupled with the programmable personal device, which is implemented to store at least one instruction identifier; and, a programmable controller ( 13 ) coupled with the programmable personal device wherein the programmable controller is configured to control functions of the programmable personal device on the basis of control parameters wherein the programmable controller is at least indirectly connected to the data communication interface and is implemented at least to accept a programming instruction ( 60 ) via the data communication interface ( 11 ) and to extract an instruction identifier from the programming instruction ( 60 ) and compare it to a stored instruction identifier and only to execute the programming instruction ( 60 ) if the instruction identifier contained in a particular programming instruction ( 60 ) corresponds to the stored instruction identifier, and otherwise not to execute the particular programming instruction ( 60 ) received, in order to prevent a plurality of external programming devices from incorrectly programming said programmable personal device concurrently, or out of sequence based on said compare of said instruction identifier received with the programming instruction to said stored instruction identifier.