SPATIALID variable;
For models that require a spatial weights matrix, the SPATIALID statement specifies a variable that identifies a spatial unit for each observation in the two data sets that are specified in the DATA= option and WMAT= option in the PROC SPATIALREG statement. The variable that is specified in the SPATIALID statement is also used to match the rows and columns within the WMAT= data set. You do not need a SPATIALID statement if no matching is needed for the two data sets specified in the DATA= option and WMAT= option. If you do need a SPATIALID statement, only one SPATIALID statement and one spatial ID variable are allowed. The values of the spatial ID variable in either the DATA= data set or the WMAT= data set cannot be missing.
The variable in the SPATIALID statement can be either numeric or character. However, the type of spatial ID variable in the two data sets specified in the DATA= option and WMAT= option must be the same. When the spatial ID variable is numeric, it needs to be integer-valued. If you specify a number that is not an integer, PROC SPATIALREG uses the integer part of that number for matching.