Inconsistency in the output when using weighting procedure

Problem

There are discrepancies among several SPSS procedures for descriptive statistics in regard to which statistics may be reported when the sum of the case weights is less than 1.0. I have assigned noninteger weights to my data so that certain cases have greater influence than others on the statistics reported. If the sum of case weights is less than 1.0 and I request descriptive statistics with the following procedures: Descriptives will display the range, minimum and maximum values of the listed variable(s), but not the mean, or sum. Frequencies will not report the range, minimum, maximum, mean, or sum. It will report the table of frequencies for each observed value. Means will report the range, minimum, maximum, mean, and sum. Explore (EXAMINE) will report the range, minimum, maximum, and mean. The sum is not available from the Explore procedure. Custom Tables (CTABLES) will report the range, minimum, maximum, mean, and sum. None of the above procedures report the variance standard deviation when the sum of weights is less than 1.0, but this makes sense as the denominator of the variance is the sum of the case weights minus 1 and this denominator must be a positive value. Why do these discrepancies exist in SPSS procedures in the situation where the sum of the weights is less than 1.0?