CGI_CLEAR_MISSING_VALUES

This variable lets you to control the behavior of the ACCEPT statement when CGI variables are empty or do not exist in the CGI input data.

By default, ACCEPT sets the value of numeric data items to zero and non-numeric data items to spaces if a CGI variable is empty or does not exist. Set the CGI_CLEAR_MISSING_VALUES configuration variable to "0" (off, false, no) if you do not want ACCEPT to clear the value of the data item in this case.