The VersionRange class (used among other for module dependencies) currently supports a very simple syntax:

• * - includes all versions
• 1.2 - matches only 1.2 exactly
• 1.2/* - matches all versions including and above 1.2
• 1.2/1.2.9 - matches all versions including and between 1.2 and 1.2.9

It'd be beneficial to be able to exclude versions in a range - currently, if you want to specify a dependency as "1.* but not 2.0", you can only use 1/1.999, which isn't elegant.. nor safe. We could support the following syntaxes - "math"-style, and Maven style:

• [1.2,1.2.9] - inward square brackets mean inclusion
• [1.2,1.2.9[ - outward square brackets mean exclusion
• [1.2,1.2.9) - parenthesis mean exclusion

Maven style is described here:

• http://maven.apache.org/enforcer/enforcer-rules/versionRanges.html
• http://docs.codehaus.org/display/MAVEN/Dependency+Mediation+and+Conflict+Resolution#DependencyMediationandConflictResolution-DependencyVersionRanges

I currently don't see a use for supporting multiple sets, although it could be useful to avoid a specific, known-buggy, version.