https://open-services.net/bin/view/Main/OSLCCoreSpecQuery secdtion Property Tree Patterns describes the oslc.properties query parameter. That spec does not define the syntax of that query parameter. However, it is defined in OSLC Core 3.0 Part 1 section 4.7 Selective Properties.

The query parameter can be used in two different contexts:
1) Selective properties for a GET of a resource. This is what is described in section 4.7.

2) Selective properties for the results of an OSLC Query. This isn't described in section 4.7. It is described in the OSLC Query spec, but there's no reference to the syntax in Core Part 1 section 4.7, and its functionality overlaps oslc.select. The spec does not clearly describe the difference between oslc.properties and olsc.select, and the Query spec has no examples of query results to explain this. I believe the intended behaviour is control which properties of the container itself are returned. In most use cases, this isn't very useful and some implementations might support oslc.select but ignore oslc.properties in their query implementation.

The whole section about property tree patterns is unclear and could do with improvement.