The Trove software map (Trove © SourceForge 2012CC by). proposes a nice set of values for this, as included in release v0.3.

 

1 - Planning

planning

http://sourceforge.net/api/trove/index/rdf#7

2 - Pre-Alpha

prealpha

http://sourceforge.net/api/trove/index/rdf#8

3 - Alpha

alpha

http://sourceforge.net/api/trove/index/rdf#9

4 - Beta

beta

http://sourceforge.net/api/trove/index/rdf#10

5 - Production/Stable

production

http://sourceforge.net/api/trove/index/rdf#11

6 - Mature

mature

http://sourceforge.net/api/trove/index/rdf#12

7 - Inactive

inactive

http://sourceforge.net/api/trove/index/rdf#358