I am not sure how to filter project area for iterations. The sample below works for categories

https://<ccm_server>/ccm/oslc/categories.xml?oslc_cm.query=rtc_cm:projectArea="_7AhiUKXxEeK8EpcidNMvow"

I refer the Kot Tontranakwong's answer.
retrieve the categories -->OK
But retrive the interations -->NG(error). Pls see the below URL. Which is wrong?

https://host.my.company.net:9443/ccm/oslc/iterations.xml?oslc_cm.query=rtc_cm:projectArea="_j3EowFXgEeOyQYTHpXYc7Q"

error info
<oslc_cm:error><oslc_cm:status>400</oslc_cm:status><oslc_cm:message>Unknown attribute id: rtc_cm:projectArea</oslc_cm:message></oslc_cm:error>

For the purpose of obtaining iteration for specific development line. Reporting Rest I/F may helps.

 https://clm.example.com:9443/ccm/rpt/repository/foundation?fields=foundation/iteration[developmentLine/name='RTC V4.0.6 Development']/(id|name|developmentLine/name)

This yields some thing like:

<iteration>
    <developmentLine><name>RTC V4.0.6 Development</name></developmentLine>
    <id>Sprint 2</id>
    <name>Sprint 2</name>
</iteration>

Unfortunately, iteration belongs to development line, so we have to query developmentLine using like:

https://clm.example.com:9443/ccm/rpt/repository/foundation?fields=foundation/developmentLine/(name|projectArea/name)

For the brief introduction to reportable RestAPI, refer to this web pages:
  https://jazz.net/wiki/bin/view/Main/ReportsRESTAPI

Good feature of this reports API is that we can query by name, not uuid of objects.