What must you maintain when using pointer control for variable input?

When using pointer control for variable input in SAS, it is essential to use specified columns for each variable and maintain the structure. Pointer control involves moving the pointer to specific locations in the input data, allowing for flexible reading of data from defined positions. This method requires that you consistently know where each variable's data begins and ends based on the column positions.

Maintaining the specified columns ensures that the data is read accurately according to the set structure. Each variable needs to be input from its designated column, so any misalignment or changes in the data format could lead to incorrect data being read. This is particularly important in scenarios where data may not come with headers or where the format is strictly defined.

The other options, while they may present valid points in certain contexts, do not address the core requirement when using pointer control for variable input. For instance, switching input styles or aligning columns without gaps are not strict necessities; the crucial aspect is adhering to the defined column structure for input. Similarly, while variable naming conventions can be important within a programming context, they do not directly relate to the mechanics of pointer control during variable input.