Commands in one form or another make things happen in TSO/E. In line mode TSO/E you issue commands in their original form. So far you have issued the LOGON and LOGOFF commands.

With panels, you issue commands in a different form by selecting options and entering information in fields. In addition, panels have commands of their own, such as the PF key commands and KEYS.

TSO/E line mode commands consist of the command name and possibly one or more operands. The command is typically a familiar word that describes what the command does; for instance, the RENAME command changes the name of a data set.

Operands provide specific information. For instance, the operands for the RENAME command are the old data set name and the new data set name. Commands can have two kinds of operands, positional and keyword.