Missing data which is not '.' are Special numeric missing values, represented by a single period followed by a single letter or an underscore (for example .A, .S, .Z, ._). And these can be assigned by using ' missing statement' (eg: missing d na; ) Now where ever data contains d or na will be considered missing value. And numeric format for these missing value can be defined thru proc format. eg: proc format; value numf .d = 'dead' .na = 'not available' ; run; Now use these numeric format for missing data which is not '.' ;