The IEQ space matrix is a key reference document for this credit (as well as several other LEED credits). Currently in its third edition as of 4/1/2013, the matrix is a spreadsheet that categorizes the spaces from the IES Lighting Handbook, 10th Edition for applicability to IEQ credits. These lists are intended to be used along with key LEED definitions for spaces such as regularly occupied spaces. Many questions about this credit can be clarified by reviewing the IEQ space matrix.