Eventually a chain will come to an end, usually with a new entrant into the system or when the last unit in a chain is abandoned, merged, or destroyed. This can involve a new employee recruit or a housing unit on the market for the first time, or when a house in the chain is torn down, left empty, or the duties of a vacant job are distributed among other employees. A vacancy chain is simply the sequence of moves that a vacancy makes from initial entry into a system to final termination. The distribution of material resources and social positions through vacancy chain processes requires that the things distributed possess a number of abstract qualities. These qualities include that the resource units in question are reusable, discrete, identifiable, and utilized by one individual or social group at a time.