A variable's name is known as an identifier. The identifier given to a variable usually follows certain rules: It can contain letters and numbers but must start with a letter. It must contain at least ...

The CONTROL statement declares control variables and specifies their values. A control variable is like a parameter except that it has a fixed value and is not estimated from the data. You can use ...

It can contain letters and numbers but must start with a letter. It must contain at least one letter (at the start of the name). It must not contain special characters such as !@£$%&* or punctuation ...