A method comprising: - identifying , in or after a second process of compiling data that yields a second navigation database , a navigation data item having a changed position in a list of said second navigation database, wherein said changed position of said navigation data item is different to a previous position of said navigation data item in a list of a first navigation database which is yield from a first process of compiling data performed before said second process of compiling data, - generating first update data for updating said first navigation database to an intermediate navigation database in a first updating step, wherein said first update data represents information for changing a data reference pointing to said previous position of said identified navigation data item to a data reference pointing to said changed position of said identified navigation data item , and wherein said first update data contains an update position list represented by a byte sequence, wherein a position of an entry in said byte sequence represents said previous position of said identified navigation data item in said list of said first navigation database and a value of said entry in said byte sequence represents said changed position of said identified navigation data item in said list of said second navigation database, - determining said intermediate navigation database at least partially based on said first update data and said first navigation database , - generating second update data for updating said intermediate navigation database to said second navigation database in a second updating step, wherein said intermediate navigation database and said second navigation database serve as inputs to said generating said second update data - identifying , in or after a second process of compiling data that yields a second navigation database , a navigation data item having a changed position in a list of said second navigation database, wherein said changed position of said navigation data item is different to a previous position of said navigation data item in a list of a first navigation database which is yield from a first process of compiling data performed before said second process of compiling data, - generating first update data for updating said first navigation database to an intermediate navigation database in a first updating step, wherein said first update data represents information for changing a data reference pointing to said previous position of said identified navigation data item to a data reference pointing to said changed position of said identified navigation data item , and wherein said first update data contains an update position list represented by a byte sequence, wherein a position of an entry in said byte sequence represents said previous position of said identified navigation data item in said list of said first navigation database and a value of said entry in said byte sequence represents said changed position of said identified navigation data item in said list of said second navigation database, - determining said intermediate navigation database at least partially based on said first update data and said first navigation database , - generating second update data for updating said intermediate navigation database to said second navigation database in a second updating step, wherein said intermediate navigation database and said second navigation database serve as inputs to said generating said second update data <EOS>