The "isParallelCompound" relation relates one Link to an ordered set of Links.
In addition, it can relate one Port to an ordered set of Ports

(Note that isSerialCompoundLink can only relate one Link to an ordered set of Links, hence it is not named "
isParallelCOmpoundLink").

It is used to describe one logical link that is comprised of multiple parallel links. Examples are:

* Link aggregation on Ethernet (IEEE 802.3ad and IEEE 802.3ax)
* 1:1 or 1+1 redundant links with primary and backup path.
* Multipath TCP (MPTCP) (RFC 6182)
* Virtual concatenated timeslots in SDH and SONET
* (likely) Equal cost multipath TCP

A proposal is required how to add additional information to the description -- e.g. what type of link it is (e.g. LACP 
or 1:1 backup), and how to specify the type of each link (e.g. which link is active for a 1:1 redundant link)