Where must line-hold specifiers appear in the INPUT statement?

Line-hold specifiers in the INPUT statement are used to control how data is read from the input data stream, particularly when dealing with formatted data or when you want to handle records in a specific manner. These specifiers, such as @ for holding the current line or @@ for holding the line across multiple iterations, need to appear at the end of the INPUT statement to function properly.

Having the line-hold specifiers at the end ensures that the SAS system understands that it should maintain the current line position for additional data reading until a condition is met to release it. This placement is crucial, as placing them at the beginning or middle of the statement would lead to unpredictable results and might cause the data to be read incorrectly.

Thus, the requirement for line-hold specifiers to appear at the end of the INPUT statement is essential for ensuring that they effectively control the reading of data as intended.