Dotty uses multiple schemes for version numbering.

Stable releases have version numbers of the form 0.${x}.${y}, where x is a main version and y is a bug-fix update id.

Release candidates version numbers have the form 0.${x}.${y}-RC${z}. Every 6 weeks, the latest release candidate is promoted to stable and becomes version 0.${x}.${y}. The release candidates let library authors test their code in advance of each release. Multiple release candidates may be released during each 6 weeks period to fix regressions and are differentiated by z.

Nightlies have version numbers of the form 0.${x}.${y}-bin-${date}-${sha}-NIGHTLY. Every 6 weeks, the latest nightly is promoted to release candidate becomes version 0.${x}.${y}-RC1.