A memory for storing user data includes one or more units. Each unit has one or more pages, each with sufficient storage space for storing both several sectors of user data and related overhead data. The storage space of at least one page per unit is partitioned among user data areas (one per sector) and one or more unit field areas. Each unit field area includes at least one unit field, and the storage space includes fewer of at least one of the unit fields than there are sectors. When unit data are stored in the unit field area, there are fewer instances of at least one unit datum than there are sectors. The storage space also includes one sector field area per sector and one sector data field area per sector, and the size of the storage space is less than the sum of the area sizes times the number of sectors.