MISSOVER
prevents an INPUT statement from reading a new input data record if it does not find values in the current input line for all the variables in the statement. When an INPUT statement reaches the end of the current input data record, variables without any values assigned are set to missing.

DELIMITER= delimiter(s)
specifies an alternate delimiter (other than a blank) to be used for LIST input, where delimiter(s) can be one of the following items.

DSD (delimiter-sensitive data)
specifies that when data values are enclosed in quotation marks, delimiters within the value are treated as character data. The DSD option changes how SAS treats delimiters when you use LIST input and sets the default delimiter to a comma. When you specify DSD, SAS treats two consecutive delimiters as a missing value and removes quotation marks from character values.

十分感谢！～