* Data Input and Output:: Reading data from user files.
* System and Portable File IO:: Reading and writing system & portable files.
* Combining Data Files:: Combining data from multiple files.
-* Variable Attributes:: Adjusting and examining variables.
+* Manipulating Variables:: Adjusting and examining variables.
* Data Manipulation:: Simple operations on data.
* Data Selection:: Select certain cases for analysis.
* Conditionals and Looping:: Doing things many times or not at all.