The messenger in triplex and quad is already determined by the wire size that is wrapped around it. It is the maximum span distance that you should find for the size of over head cable that is being used.

A messenger wire is a wire or cable that is used solely for the physical support of another element, typically a conductive wire or bundle of wires. The messenger wire will take the shape of a parabola (shape of a free hanging string) and the conductive wore or bundle of wires supported by the messenger may follow that parabola of be supported in a straight lines through the use of drop lines. Take a look at the power catenary for a light rail or electrified bus system.

A messenger who is Greek.

m stands for messenger, mRNA is messenger RNA

Windows Messenger was created by MSN in 1999. It was then the competitor of AOL Instant Messenger. It was later known as MSN Messenger.