I was wondering if something like this can work: Given a ConfigurationOfProject (a subclass of ConfigurationOf) defining: stable: spec <symbolicVersion: #stable> spec for: #'pharo4.0.x' do: [spec baseline: 'Project' with: [ spec repository: 'github://username/Project:stableForPharo4/']]. spec for: #'pharo5.0.x' do: [spec baseline: 'Project' with: [ spec repository: 'github://username/Project:stableForPharo5/']]. where stableForPharo4 and stableForPharo5 are tags in the git repo (and assuming the BaselineOfProject is defined in this commits). Is this supposed to work : Metacello new configuration: 'Project'; repository: 'github://username/Project:master'; version: #stable; load. ?? I've tried using a non-symbolic version and it works but I can't make it work for #stable. I'd like to use this configuration for the Configuration Browser/Catalog Browser. Any help is appreciated.