This document uses an analysis of the State Estimation use case to propose a set of IDL interface classes for a Data Acquisition component that can be used in other, yet to be defined, use cases. Since Measurements are a very generic entity, this interface specification may cover a wide range of use cases that involve the transfer of telemetered data from a Data Acquisition application. It is likely to be equally applicable to Automatic Generation Control or updating user interfaces. The main difference between the client applications is in the way they select which measurements are of interest. The other difference is that there is likely to be only one State Estimator in the system but there will be many user interfaces. Within this document CIM_ is used as a prefix for entities within a component as if they were directly implemented using the Common Information Model (CIM) as a schema. CIS_ is used as a prefix for Component Interface Specification structures and classes.