What is the function of the MISSOVER option in the INFILE statement?

The MISSOVER option in the INFILE statement is designed to enhance how SAS reads data files. When MISSOVER is specified, SAS will not advance to a new line until it has reached the end of the current line of input, effectively preventing it from looking for additional data that may not be present. This is particularly useful when dealing with fixed-width data files, where certain fields may not fill an entire row. By using MISSOVER, SAS reads the data line by line, ensuring it processes only the data in the current row and does not erroneously attempt to populate variables with data from subsequent rows if the current row is short.

The key function of this option is to maintain control over how the data is read and to avoid unexpected results from misaligned data. It ensures that if the specified number of variables is not met in a row, SAS simply fills the missing values with user-defined missing indicators instead of advancing to the next line. This behavior helps maintain the integrity of data processing in situations where row lengths may vary.