CMPI association provider

Hi folks,

got some questions on CMPI association provider.  But I will stat out with
basic question.

I did searched on the message archive but didn't find the one I was looking
for.  So here I am.

OK,

on this document

   -
   http://www.dmtf.org/apps/org/workgroup/applications/metricextensions/download.php/38074/DSP1053_1.0.0.pdf
   [note: may have to sign in before you can access above document]

It says required functions as [ on page 27] remember that *CIM_MetricDefForME
is an assocation class*

 Associators
AssociatorNames
References
ReferenceNames
EnumerateInstances
EnumerateInstanceNames

on this docment

   - http://www.wbemsource.org/uploads/40/3712/CMPI.pdf\<http://www.wbemsource.org/uploads/40/3712/CMPI.pdf/>

It says required fucntions as [on page 32]

 Associators
AssociatorNames
References
ReferenceNames

I am little bit confused which functions are must ???

Thanks much.......got others questions as well but will do some more
reading....