How to use oslc.query in the RTC RESTful simply query interface

I am trying to write some Perl code to use the RESTful interface on RTC to access workitems.  I am able to get the simpl_query_services URI as described in https://jazz.net/library/article/1001 and  https://jazz.net/wiki/bin/view/Main/WorkItemAPIsForOSLCCM20.   When I use the basic URI, eg

https://myjazzserver.com:9443/jazz/oslc/contexts/_8IloQGRKEeGMeeKcLm-Fsg/workitems

then all seems to work well and I get a collection of workitems returned (in fact all the workitems in the Project).  However, I have not been able to work out how to do a 'where' query to select a subset of these workitems, eg

https://myjazzserver.com:9443/jazz/oslc/contexts/_8IloQGRKEeGMeeKcLm-Fsg/workitems?oslc.where=dc:identifier="1832"

again returns all the workitems in the project.  In fact, whatever I put in the where clause seems to have absolutely no effect.  Can anyone say what the correct syntax is for these types of queries?  I want to be able to do queries based on id and also on workitem type, which seems to be a more complex resource type.  For instance we have a workitem type called 'build' in our project,  and i would like to be able to find all the workitems of that type.  The type is indicated in the workitem description by elements such as

<dc:type rdf:resource="https://jazz201.hursley.ibm.com:9443/jazz/oslc/types/_8IloQGRKEeGMeeKcLm-Fsg/build"/>

so how should I construct a query to find all these items - i tried

https://myjazzserver.com:9443/jazz/oslc/contexts/_8IloQGRKEeGMeeKcLm-Fsg/workitems?oslc.where=dc:type="build"

but this does not work.  How does the oslc_prefix parameter play in all of this?

Any help or examples greatly appreciated.