A variable is a reference to a piece of information. The following lines each contain an example of a variable:
You create a variable by using one of the following elements:
Not every name is is a valid variable name. The name of a variable can only be constructed with a combination of letters, numbers and the underscore _. One additional condition is that the name of a variable must start with an alphabetic character. Examples of valid variable names are:
The following names are not valid variable names:
rate-code /* the hyphen is not allowed */
20characters /* the name must start with an alphabetic character */
first&last /* the punctuation mark & is not allowed */
The value of a variable is always of a certain type. This type determines the ways this information can be used and manipulated by keys.