ULTAREAUNIT (V004) reports the ultimate area unit for the person's de facto residence.
According to the DHS recode manuals, ULTAREAUNIT
is a number assigned to each sample point to identify the ultimate area units in the collection of data. It is usually the same as the cluster number [CLUSTERNO (V001)], but may be a sequentially numbered variable for samples with a more complicated structure.
ULTAREAUNIT can be used to account for the impact of the sampling design clustering on the variance estimates and standard errors.