Search function for portable navigation device

A portable navigation device or navigation system comprising:

• a display;
• memory including one or more map data files comprises digitized map data and descriptive data identifying features represented within said digitized map data;
• processing means;
• wireless signal reception means;
• user interface arranged with said display, memory processing means and reception means to receive user input;
• software arranged with said processing means to perform navigation between a current location determined from wireless signals received by said reception means, and a destination at least partially identified by said user input, wherein said software includes an address finding facility which when selected, causes display of at least one address portion identifier on said display together with a first sorted list of consecutive alphanumeric characters being both selectable and representing either
• a first alphanumeric character of said address portion identifier, or
• a first range of alphanumeric characters between which said address portion identifier exists,
• means for displaying a second list of alphanumeric characters in response to selection of an entry in said first list, wherein entries in said second list are selectable and include either
• said first alphanumeric character and at least one further alphanumeric character, said further alphanumeric character consecutively changing in said second list, or
• a second narrower range of alphanumeric characters, or
• individual consecutive alphanumeric characters previously represented by said first range, and
• wherein selection of an entry in said second list causes either identification of said address portion identifier or display of further lists being progressively more specific as a result of user selection of entries in previously displayed lists until selection of an entry in one of displayed further lists results in such identification.