This is used by the DCCD webapplication. For documentation see the DCCD webapplication README.md
If the build fails when trying to build an RPM package, with an error similar to this:
RPM build execution returned: '1' executing '/bin/sh -c cd '/Users/paulboon/git/service/dccd/dccd-lib/target/rpm/dccd-lib/SPECS' && 'rpmbuild' '-bb' '--target' 'noarch-apple-mac os x' '--buildroot' '/Users/paulboon/git/service/dccd/dccd-lib/target/rpm/dccd-lib/buildroot' '--define' '_topdir /Users/paulboon/git/service/dccd/dccd-lib/target/rpm/dccd-lib' 'dccd-lib.spec'' -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.codehaus.mojo:rpm-maven-plugin:2.1.3:rpm (generate-rpm) on project dccd-lib: RPM build execution returned: '1' executing '/bin/sh -c cd '/Users/paulboon/git/service/dccd/dccd-lib/target/rpm/dccd-lib/SPECS' && 'rpmbuild' '-bb' '--target' 'noarch-apple-mac os x' '--buildroot' '/Users/paulboon/git/service/dccd/dccd-lib/target/rpm/dccd-lib/buildroot' '--define' '_topdir /Users/paulboon/git/service/dccd/dccd-lib/target/rpm/dccd-lib' 'dccd-lib.spec''
then you may have to externally define one of the macros of the rpmbuild tool. Create or edit the file ~/.rpmmacros and add the following line:
%_tmppath %{_topdir}/BUILD