Meaning of negative counterId/values with MetricCSV?

Good day,
I'm busy writing an python app to pull all the performance data from the ESXi hosts as quickly as possible.

Using the following code snippet, I get some negative counterId values as below. Are those values to ignore? And if it's "useful", how do I map that negative counterId to the relevant counterId/value?

for vm in gpOutput:
    print(vm['moref'])
    qs.append(vim.PerformanceManager.QuerySpec(entity=vm['moref'], startTime=startTime, endTime=endTime, instance='*', format='csv'))
print("perfRes")
perfResults = perfManager.QueryPerf(querySpec=qs)

         (vim.PerformanceManager.MetricSeriesCSV) {
            dynamicType = <unset>,
            dynamicProperty = (vmodl.DynamicProperty) [],
            id = (vim.PerformanceManager.MetricId) {
               dynamicType = <unset>,
               dynamicProperty = (vmodl.DynamicProperty) [],                                                             
               counterId = -2147483542,   
               instance = ''
            },
            value = '-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-
1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1
,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,0'
         }

Start with the PerformanceManager.QuerySpec and MetricSeriesCSV entry points shown in the report, then consult the pyvmomi and vSphere PerformanceManager documentation for counterId semantics. Determine whether negative counterId values and -1 samples are expected, and document how such values should be interpreted or mapped.