Release 5.1
The method for counting book usage has changed. In COUNTER 5.1, each item used (chapter, reference entry, article) is counted as a Unique_Item_Investigation or Unique_Item_Request. Consequently, the "SN:Total_Chapter_Requests" custom metric becomes obsolete and is no longer available.
We use all Metric_Types listed in the COUNTER code of practice, except for Searches_Automated, Searches_Federated & Limit_Exceeded.
Release 5.0
Our custom Metric_Type SN:Total_Chapter_Requests was introduced to help you compare book requests in C4 with requests in C5.0.
We started providing data for the Metric_Types at different points in time. Some data is available from January 2016 while data for other Metric_Types is available from a later date. Details are available per platform in the article “Platforms in COUNTER reports”.