For simple indexes, the name of the index is the same as a variable in the data set. Unique Option indicates whether the index must have unique values. If the column contains YES, the combination of values of the index variables is unique for each observation. Nomiss Option indicates whether the index excludes missing values for all index variables. If the column contains YES, the index does not contain observations with missing values for all index variables.
Variables names the variables in a composite index.
Sortedby indicates how the data are currently sorted. Validated indicates whether PROC SORT or PROC SQL sorted the data. Character Set is the character set used to sort the data. Collating Sequence is the collating sequence used to sort the data set. This field does not appear if you do not specify a specific collating sequence that is different from the character set.