Variables are often used phrases (such as product names)
that are re-used by replacing the value of the variable at the time the
information is published.
Variables using conref and filtering
Single-source publishing relies heavily on the concept of variables. While DITA does not have a specifically named variables feature, it does readily support variables functionality.
Variables using indirection
The keyword element can be used as a container for variable words and phrases, when used in conjunction with the keydef element in the ditamap. Rather than enter the value of the keyword directly into the element, you can indirectly reference it through a key.