+ which includes the major milestones.
+ </div>
+ <div xmlns:ld="http://lambdadelta.info/" class="text">
+ The life cycle of a specification consists of four periods.
+ <span class="emph alpha">Alpha:</span>
+ the definitions are designed and the major propositions are proved,
+ then the calculus is announced with a presentation.
+ <span class="emph beta">Beta:</span>
+ major changes and additions may occur before the calculus is released on paper.
+ <span class="emph gamma">Gamma:</span>
+ subsequent improvements occur until the specification is completed or superseded,
+ while major changes and additions are announced and reported on paper.
+ <span class="emph delta">Delta:</span>
+ after its conclusion, the specification is modified just for maintenance.