I've put up code for JSON-RPC (server only for now, tested with some Python client) on SS3. The code uses Sven's excellent Zinc and NeoJSON libraries. I'm now writing a ConfigurationOf. The current release of NeoJSON, going by its ConfigurationOf, has Neo-JSON-Core-Sven.27. However, I am using Neo-JSON-Core-Sven.29, which has NeoJSONWriter>>writeNil: required by the JSON-RPC spec. How should I express this dependency in JSON-RPC's ConfigurationOf? At present it looks like this (monkey-see monkey-do using some other configuration): spec project: 'NeoJSON' with: [ spec className: 'ConfigurationOfNeoJSON'; loads: #('Core'); repository: ... ] Thanks. Maybe if Sven reads this he can mark .29 as the stable release. That'll work too. :-) Pierce