Complex sentence: The Senior Members are a selected group who are entitled to hold specific IEEE officer positions and is the requirement for those who are nominated and elevated to the grade "IEEE Fellow", a distinctive honor.
Split into simpler sentences: The Senior Members are a selected group, and certain IEEE officer positions are available only to Senior (and Fellow) Members. Senior Membership is also one of the requirements for those who are nominated and elevated to the grade "IEEE Fellow", a distinctive honor.