This paper focuses on time-based declarative languages. The use of declarative languages has the advantage of their simplicity and gh-level abstraction, usually requiring few or no programming skills. Moreover, in general, declarative languages benefit portability and allow automatic control of application execution temporal flows, without author awareness. However, most time-based declarative languages have limited support for variable definition and manipulation, which causes developers to resort to imperative languages. This paper discusses and proposes an approach for variable handling in XML-based declarative languages used for temporal synchronization among media objects that balances flexibility and simplicity. An important goal is to resort to imperative languages only for those applications that require intensive algorithmic computation. The proposed solution was adopted by the NCL declarative language of the Brazilian DTV System. Categories and Subject Descriptors I.7.2 [Doc...