How to use variables

WML variables as parameters gives an  ability to  create contents dynamically and navigating based on user input. 

The setvar element specifies a variable and can be used in the task elements. User input elements use variables too:

Variable names consist of a US-ASCII letter or underscore followed by a zero or more letters, digits, or underscores. Variable names are case-sensitive. 

Parentheses are required anywhere the end of a variable cannot be inferred from the surrounding context. The following examples demonstrate legal variables:

$var
$(var).
$(var:e).
$(var:unesc).
$(var:N).

A single dollar sign entity, even when specified as $, results in a variable substitution. Two dollar signs are replaced by a single $ character. For example:

This is a $$ character.

would be displayed as:

This is a $ character.

A single dollar sign entity, even when specified as $, results in a variable substitution. To include the $ character in URL-escaped strings, specify it with the URL-escaped form %24.