The Library seeks to build comprehensive collections where relevant materials are acquired to the greatest extent possible; representative collections where the Library selects a manageable amount of material to represent a type, creator or subject; and selective collections where items of national priority or special significance are identified and collected, or where depth of collecting is prioritised above breadth. This section of the policy is arranged in sequence from comprehensive to selective, recognising that such a continuum is neither fully linear nor completely exclusive. Web archiving for example, falls midway along this imaginary line, and is by turns comprehensive, selective and representative.