International Polar Motion Service

Project Description
In 1962 the ILS was renamed the International
Polar Motion Service (IPMS) and in 1988 the IPMS was discontinued when
the International Earth Rotation Service commenced. During its history
the ILS/IPMS provided valuable observations of polar motion which
continue to be analyzed today.

Information provided by http://igscb.jpl.nasa.gov/mail/igsmail/1998/msg00249.html