What does the @@ symbol indicate when reading in raw data?

The @@ symbol in SAS is used to indicate that the input statement should read multiple values from the same line of data. It allows SAS to continue reading the same line for more variable values until it encounters a line break. This is particularly useful when you have more data values on a single line than variables defined in the input statement, or when you want to control how the data is read without moving to a new line.

Using the @@ symbol facilitates reading in additional observations or maintaining the read position on the same line, which makes it an effective tool for efficiently managing larger sets of data that are formatted in a row-wise manner.