Splus objects are stored in the .Data directory and are saved from one session to the next. In order to save a data object, a name must be assigned to it. The name must start with a letter and may contain letters, digits, and periods. Splus is case sensitive, x and X refer to two different things. Functions use the arguments provided in parentheses to perform a task.
Subscripts require square brackets.
The information provided in square brackets tells Splus what subset of a data object is being referred to. The data objects you have just created are stored in your .Data directory. You can also remove more than one data object at a time. This will cause the warning message to be printed one last time. Print the number of rows in the matrix.