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:
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.