[libvirt] Memory allocation/usage

We are trying to understand the memory allocation and usage for a KVM guest using the libvirt java API version 0.5.0. A certain memoryStats(int) on the Domain class allows you to fetch MemoryStatistic values. Each of this statistic has a tag and a value. In our case, the values returned were [tag: 6 val:8388608 , tag:7 val:8466792 ] What are these tag values(6 and 7) representative of? Do they mean memory allocated and memory used. If yes, how can we confirm that?