The syntax and semantics of timed $\mu CRL$

We define a specification language called `{\it timed $\mu CRL$}''. This language is designed to describe communicating processes employing data and time. Timed $\mCRL$ is the successor of $\mCRL$ \cite{GroPo94a}. It differs in two main aspects. It is possible to make explicit reference to time using a new `{\it at}'' operator; $p\at{t}$ is the process $p$ where the first action must take place at time $t$. Furthermore, a distinction has been made between constructors and functions in the datatypes. Care has been taken that every $\mu$CRL specification is also a correct timed $\mu$CRL specification with exactly the same meaning.